Empathy is probably the single most important difference between a good hacker and a great one. - Paul Graham

If you disagree with something, it's easier to say 'you suck' than to figure out and explain exactly what you disagree with. You're also safe that way from refutation. In this respect trolling is a lot like graffiti. Graffiti happens at the intersection of ambition and incompetence: people want to make their mark on the world, but have no other way to do it than literally making a mark on the world.

It's exhausting to be lied to. I think some of the most accomplished liars even take advantage of this fact. Their lies then serve a double purpose: (a) whatever purpose each specific lie serves and (b) to exhaust their audience and thereby batter them into submission.

It's a dangerous skill to be good at convincing yourself that you don't want things you worry you might not get. Useful in some areas perhaps, but disastrous in others.