Geeks enjoy being Libertarians for two reasons. First, it allows them to be Conservative without having to belong to one of the two mainstream parties that the regular sheep are part of. Second, it gives them a political party that is just as self-absorbed as they are. Conservatives don’t care if you think they’re selfish pricks. Libertarians wonder why you don’t admire them for it.
Since many geeks are unable to care about or even imagine the existence of the feelings of anyone other than themselves, the fact that Libertarianism ignores the unpleasant reality that we live in a society that requires certain things to function is not a problem to them. As far as geeks are concerned, society is lost anyway since it refuses to respect the geeks as the superior members. (The collapse of society is perfectly fine with the geek since it would allow him to act out his post-apocalyptic fantasies in which he would be a dune-buggy driving, grenade launching warlord, in defiance of all the evidence that demonstrates a more probable outcome.)
Libertarianism assures the white male upper-middle-class geek that he has gotten where he is solely because of his big brain and amazing talent for knowing the entire history of Middle-Earth. It assures him that he is the master of his destiny, the only force responsible for his fate. He owes no favors nor allegiance to anyone else. He is his own ideal. Most geeks reading that paragraph are now re-reading it slower and will soon achieve orgasm.
Of course, the other benefit to Libertarianism is that it doesn’t come with all that religious baggage that the Republicans come with. Geeks love not being Christians (Spoiler!) so the Libertarian Party is a better fit for them. It also doesn’t hurt that since the Libertarians never win anything, they can be an actually reviled minority instead of a pretend one like the Conservatives.
Some famous Libertarians are Penn Jilette, Matt Stone, Trey Parker, Robert Heinlein, Ayn Rand, Matt Drudge, and Howard Stern. Possibly related is the fact that all of the above are also assholes.
A political affiliation where they are the smartest people on Earth and everyone else can go screw themselves? No wonder geeks LOVE Libertarianism!