Keyboard cowboys. I think this is one area where I disagree with you Killa. Trolling isn't done to enjoy other people's misery, it's done to laugh at how pissed off a person gets. If you get upset over a video game, you've got odd priorities.
Getting upset over a video game is something like getting mad when you die. Getting upset at a hacker ruining your fun is a completely different story. Not to mention most of the "trolling" is done not in game but on this forum where people just want to talk.
Enjoying other people's misery and laughing at people getting mad is essentially the same thing. Maybe misery was too strong of a word to use, but I can't think of anything that would fit perfectly right now.
Point is, people are simply trying to have fun and if you enjoy ruining that, there is something wrong with your life.