> To add to your point, nobody actually trolls in person or in real life because 1) the body language gives them away immediately and 2) they're risking getting punched in the face for their effort.
A couple of people already got to it before me, but I wanted to add on: plenty of people do troll in meatspace.
I don't think it is quite as effective as online trolling, and certainly doesn't have the same impact to effort ratio, but it happens.
When some kid calls in a bomb threat to get out of school (happened to my Middle School post-9/11), it has an effect largely contained to that school and the immediate vicinity around it. When somebody trolls online, it has a much more subtle effect, but with enough contributors over enough time, a potentially more poisonous effect on society.
In the first instance cops can come in and clear the building discovering there is in fact, zero bombs (or alternatively, there is, but I've never personally seen that happen). In the second instance, you have a faceless group of people that are shaping and poisoning debates or preventing them from even occurring in the first place, helped by the very platforms they're trolling on. Fear, uncertainty and doubt has always been easy to spread around like so much manure, not so much with the antidotes to FUD because it is basic human nature to be cautious and skeptical of that which is different from what they know, or beyond their understanding.
In meatspace you also have more dimensions through which to interpret someone's intended message: body language, tone, choice of words, facial language, gestures, whether they can stifle their laughter and so on, and even all of that might not be enough (trolling people is easy even in meatspace, even if you're half-laughing when you do it and is a common enough flirting gesture). Cyberspace, you often only have what they wrote, and how they wrote it. It really isn't the same.