A troll is a sadist.
This observation just coalesced for me. It perfectly explains why I revile trolls. The only thing a troll does is try to hurt people, often by making them angry, but ALWAYS by reveling in the pain and chaos that the troll spreads: and that is the salient point. The troll is not just disseminating lies. The troll is being gratified by the pain s/he spreads. That is a sadist. Now I understand better why my dander flares up when I see some asswipe post something like “Great trolling, man.” That asswipe is applauding a sadist.