1) Politics. There is WAY too much vitriol, and the fact is people simply do not know how to have civil, respectful disagreement as ladies/gentlemen anymore. All it takes is one line for the insults to start flying. Especially when you're in an environment where a lot of groupthink is going on (and believe me, both sides are capable of creating and maintaining such environments), and you happen to go against the party line. Until people learn how to debate civilly again, then I want no part of it. Keep your nasty resentments and superiority complexes to yourself.
There are other topics I hate...I'll add them later.