He theorizes that conservative pessimism keeps conservatives from being disappointed as often as liberals, and lets them be pleasantly surprised when things turn out alright. More importantly, they rely on themselves, not government, to pursue & produce their own happiness:
...because pessimistic conservatives put not their faith in princes — government — they accept that happiness is a function of fending for oneself. They believe that happiness is an activity — it is inseparable from the pursuit of happiness.
The right to pursue happiness is the essential right that government exists to protect. Liberals, taking their bearings, whether they know it or not, from President Franklin Roosevelt's 1936 State of the Union address, think the attainment of happiness itself, understood in terms of security and material well-being, is an entitlement that government has created and can deliver.
So where does this leave libertarians? Well, libertarians certainly seem to be in agreement on the latter point about the pursuit of happiness. Further, it seems that libertarians are often even more pessimistic/cynical than conservatives. But are they, and, more importantly, should they be?
The plight of the libertarian in today's statist world was conveyed well by the brilliant Murray Rothbard in his essay, H. L. Mencken: The Joyous Libertarian.
Any man who is an individualist and a libertarian in this day and age has a difficult row to hoe. He finds himself in a world marked, if not dominated, by folly, fraud, and tyranny. He has, if he is a reflecting man, three possible courses of action open to him: (1) he may retire from the social and political world into his private occupation: in the case of Mencken's early partner, George Jean Nathan, he can retire into a world of purely esthetic contemplation; (2) he can set about to try to change the world for the better, or at least to formulate and propagate his views with such an ultimate hope in mind; or, (3) he can stay in the world, enjoying himself immensely at this spectacle of folly. To take this third route requires a special type of personality with a special type of judgment about the world. He must, on the one hand, be an individualist with a serene and unquenchable sense of self-confidence; he must be supremely "inner-directed" with no inner shame or quaking at going against the judgment of the herd. He must, secondly, have a supreme zest for enjoying life and the spectacle it affords; he must be an individualist who cares deeply about liberty and individual excellence, but who can – from that same dedication to truth and liberty – enjoy and lampoon a society that has turned its back on the best that it can achieve. And he must, thirdly, be deeply pessimistic about any possibility of changing and reforming the ideas and actions of the vast majority of his fellow-men. He must believe that boobus Americanus is doomed to be boobus Americanus forevermore. Put these qualities together, and we are a long way toward explaining the route taken by Henry Louis Mencken.
While conservatives may object to big government as merely inefficient, wasteful, and ineffective, libertarians tend to be much more concerned about the rights being violated by big government programs, both through coercive funding and through the direct and indirect effects of the programs. Further, most libertarians tend to envision a much smaller role for government (perhaps even none at all!), than most conservatives (and don't even get me started on the neo-cons). Given that the current world seems much further from the libertarian ideal than the conservative ideal - and there's no clear path towards achieving libertarian political goals - there seems to be a current of despair in some libertarian circles.
There's a tendency for those in these melancholy circles to feel that they are part of The Remnant, a phrase coined by the great Albert Jay Nock to describe the beseiged pocket of individualist holdouts against the tidal wave of statism. But perhaps they forget that the normally gloomy (his autobiography was entitled Memoirs of a Superfluous Man because he felt himself so out of place and irrelevant in the mid-20th Century) Nock's conception of The Remnant was not entirely pessimistic, but actually somewhat hopeful. As he wrote in his classic 1936 essay Isaiah's Job, to those who might consider being "prophets" of The Remnant:
There is a Remnant there that you know nothing about. They are obscure, unorganized, inarticulate, each one rubbing along as best he can. They need to be encouraged and braced up because when everything has gone completely to the dogs, they are the ones who will come back and build up a new society...You do not know and will never know who the Remnant are, or where they are, or how many of them there are, or what they are doing or will do. Two things you know, and no more: first, that they exist; second, that they will find you.
Back in 1965, Murray Rothbard rejected the link to conservative pessimism in Left and Right:
The Prospects for Liberty and suggested that while short-term prospects may seem dim, "the proper attitude for the Libertarian to take is that of unquenchable long-run optimism." He then laid out the libertarian victory strategy:
What the Marxists would call the “objective conditions” for the triumph of liberty exist, then, everywhere in the world and more so than in any past age; for everywhere the masses have opted for higher living standards and the promise of freedom and everywhere the various regimes of statism and collectivism cannot fulfill these goals. What is needed, then, is simply the “subjective conditions” for victory; that is, a growing body of informed libertarians who will spread the message to the peoples of the world that liberty and the purely free market provide the way out of their problems and crises. Liberty cannot be fully achieved unless libertarians exist in number to guide the peoples to the proper path. But perhaps the greatest stumbling block to the creation of such a movement is the despair and pessimism typical of the Libertarian in today’s world. Much of that pessimism is due to his misreading of history and his thinking of himself and his handful of confreres as irredeemably isolated from the masses and, therefore, from the winds of history. Hence he becomes a lone critic of historical events rather than a person who considers himself as part of a potential movement which can and will make history. The modern Libertarian has forgotten that the Liberal of the seventeenth and eighteenth centuries faced odds much more overwhelming than those which face the Liberal of today; for in that era before the Industrial Revolution, the victory of liberalism was far from inevitable. And yet the liberalism of that day was not content to remain a gloomy little sect ; instead, it unified theory and action. Liberalism grew and developed as an ideology and, leading and guiding the masses, made the revolution which changed the fate of the world. By its monumental breakthrough, this revolution of the eighteenth century transformed history from a chronicle of stagnation and despotism to an ongoing movement advancing toward a veritable secular utopia of liberty and rationality and abundance. The Old Order is dead or moribund; and the reactionary attempts to run a modern society and economy by various throwbacks to the Old Order are doomed to total failure. The Liberals of the past have left to modern Libertarians a glorious heritage, not only of ideology but of victories against far more devastating odds.
Indeed, there are an increasing number of optimists in the libertarian camp who have an optimistic take on the prospects for liberty. Many tend to view the rapid growth of technology & global markets, as well as anti-authoritarian social & political trends, as forces that will ultimately reduce the power and control of the state, and protect the rights of individuals. As life expectancy and standards of living continue to steadily climb, concurrent with the exponential increase in global wealth, the prospects of individuals to live long, healthy, wealthy lives seems dramatically better than in the past. While many in the mainstream find postmodernism bleak & disturbing, libertarians take heart in its portrayal of the inevitable rise and eventual global pervasion of capitalism. And while many in the mainstream also condemn the culture of consumerism, libertarians tend to bask in the power it gives to individuals to shape their own lives.
In some ways, technology and the global consumerist market helps create an end-run around statist interference in people's lives, enabling individuals to more easily acquire what they want, do what they want, associate with who they want, live how they want, despite government bans or regulations. Indeed, the future appears to be one full of (meaningful) choices - with the sheer availability of so many different forms of art & entertainment, so many different potential sources of information, so many different ways to interact with others (despite physical distances), so many different goods & services, so many different ways to make a living, so many different ways - in other words - to live one's life.
While the power of the state is unlikely to abate much in the near future, it's ability to actually control people's lives may be withering under the advances of technology and global consumerist markets. Despite the coninued existence of Big Brother, libertarians should take heart in the fact that the future is looking quite bright for the opportunity of individuals to live their lives in a way of their choosing, making meaningful choices that enable them to define their own priorities and values, without the approval or authorization of the state.

So if the State isnt in control, the corporations will have to fill the void of 'interference' in people's life.
"with the sheer availability of so many different forms of art &entertainment"
controlled by a few companies, and select special interest groups...
I'm not sure why the void of 'interference' is one that needs to be filled, nor is it at all clear how corporations will gain the power to coercively interfere in the manner that is assumed to be the very essence of the function of a state.
It seems you have an awfully pessimistic view of the world to suggest that the void of 'interference' in people's lives must be filled one way or another, so we'll either have statist or corporatist tyranny. Evidently tyranny is just a zero-sum game - there can't be less or more, just different people in control. But if that's your outlook, why not give up? There's little to suggest that states, who killed more of their own people - 100-200 million or more - in the 20th Century than were killed in all 20th Century wars combined (about 40 million), will do a better job than corporations, for which there is little/no evidence of similar atrocities (particularly when you set aside situations in which corporations were only able to behave coercively because of the actions or assistance of a state.)
"controlled by a few companies, and select special interest groups..."
I'm sorry, but LOL. That's such a tired, worn-out, silly, nonsensical argument by now. In an age of blogs, Internet news sites, newsgroups, discussion boards, listservs, online magazines &newspapers, online TV &radio shows, fanfic sites, lapsed copyright literature sites, online books, downloadable e-books, online films, online art galleries, online art stores, wide commercial availability of all forms of art, DVDs, low-cost digital film equipment and DVD burners that enable anyone to distribute a DVD or online film, DVD delivery services such as Netflix, independent theaters, wide distribution of independent films, low-cost computer equipment &cheap/free website hosts, online digital music sites &software, CDs, widespread independent CD labels, low-cost recording equipment and CD burners enabling anyone to produce &distribute an album, &widespread cable &satellite television, satellite radio, worldband/ham/CB radios, regular AM/FM radios, newstands &bookstores that carry hundreds if not thousands of print periodicals and newspapers, bookstores that carry far more books than in the past - and don't tell me they don't stock&sell tons of Noam Chomsky &Howard Zinn - combined with online bookstores that offer access to virtually any in-print and many out-of-print books, low-cost desktop publishing that enables anyone to publsh their own book/manuscript/zine/newsletter/political pamphlet, not to mention other developing technologies like podcasting, audio/videoblogging, video &Internet accessibility via a mobile divice, as well as a zillion things I'm probably forgetting, how can you seriously think that art &information is controlled by a few companies and special interest groups???
There is more art and more information available from more sources to the average person now than at any point in human history, and there is less control over how/whether that person gets that information/art than at any point in human history. I have far more access to information from a far wider variety of sources about my many bizarre and non-mainstream interests now than I did ten years ago, and than anyone on earth had twenty years ago.
republicans are always poo-pooing dems for utilizing big government, but in reality repubs are way more responsible for big government encroaching on our lives than dems...so much more in fact that the cries of limited government from repubs are ludicrous to the infinite degree.