So what exactly makes a troll want to troll?

So far, I've got it narrowed down to a few things:
  • The want to impress friends.
  • Hate against whatever they're trolling
  • Boredom
  • They're having a bad day

These look like good answers, but I'm not really sure about it. I mean, if you show your friends what how you trolled on something, won't their reaction be more like "wtf, that's not nice. Not cool bro." instead of "LOLOLOL you really showed that noob!"

Hating on the subject at the matter is basically being biased as opposed to having an open mind. This is probably the closest-looking answer, but still doesn't answer why.

Out of boredom seems like the most sensible reason, but there's no way anyone would say "This guide is a piece of S***. You suck." when the guide was actually well written, or at least the author put in a fair amount of time into it.

Having a bad day doesn't entitle you to making everyone else's day bad, but instead the bad mood will eventually go back to you one way or another. Why not just eat a cookie?

Anyone else have any idea why people troll?