I voted. Why? Who can say. Unless the outcome is decided by one vote, it wouldn't have mattered whether I voted or not. Game theory suggests I'm just playing a mixed strategy Nash equilibrium, but the problem with that theory is that I always vote; I don't randomize my decision like the Nash equilibrium strategy says I should.

Perhaps it's a social thing. I vote so I don't have to give an embarrassing look when people ask me if I voted. Also, so that if someone asks me how they should vote on a particular issue, I retain credibility with them when I tell them what I think. In that way, perhaps by voting I am actually influencing more than just one vote.

Voting is also especially pragmatic in California, where many laws are determined by popular referendum. If you don't want the government breathing down your neck any more than it already is, you need to vote against their crazy policies.