> That’s such a foreign concept to me. Some people just honestly don’t have to hold back because they are just not like that, at least not all the time.
Some people don't, sure. I was trying to make a generalization of what humans as a group are statistically likely to do; breaking it down, some humans would be assholes all the time, some a few rare times, and some never at all. (Side-point: don't feel the need to defend yourself from statistical assertions about human behavior, they're not intended as accusations: http://www.overcomingbias.com/2015/04/about-isnt-about-you.h...)
There are indeed real people who have real rage that they don't get to express as often as they'd like, though. There are people with anger management problems, or aggressive mania. There are people feeling intense (sometimes justified!) frustration in some part of their lives. There are people who are just plain sadists, and either don't know there's such a thing as a willing masochist or can't find one.
Let me draw a parallel: road rage. Depending on the culture of a particular area of the world, road rage can be either taboo or permitted. People everywhere get frustrated at the behavior of other drivers around them; that is never in question. It's only whether they choose to let those other drivers know about it that changes with each culture.
I do agree that it's possible some percentage of the assholish behavior is performance. (Though as I waved-vaguely-at in my previous post, if you can detect this sort of thing—read the intention in it—it stops actually seeming assholish and becomes more like friendly jibing. A large part of the point of 4chan is to engage in a digital communal game of https://en.wikipedia.org/wiki/The_Dozens, and a large part of becoming "part of" 4chan's community is building up a tolerance to this.)
But real asshole behavior—not the clever insults written with a cool head, but rather the seek-and-destroy-the-vulnerable bullying that harkens grade school—is not something you do to seem clever or liked. In the real world, in small communities, it can maybe win you "friends" through intimidation (thus why some real-world bullies do it), but on an anonymous forum there's just no gain in doing it but to hurt the other person. The sort of actually-hurtful things said by a bully aren't celebrated as successful roasts; they're just sort of left to sit there. When playing the Dozens, you don't poke at actual hard spots in the other person's life; it's bad form.
Now, of course, there are sociopaths who enjoy causing chaos and "stirring shit": the Iagos and Izaya Oriharas of the world. And 4chan attracts these sorts of people as well. But as much as they're a negative force—encouraging people to cut off their toes, arranging raids, etc.—they're rarely visibly assholes. In fact, they have to be a bit charismatic to get people dancing the way they want. And, oddly, 4chan seems to "hold" these sort of people at bay, as well; they identify with the community, attacking its enemies (Tumblr, say) and its obvious unaccustomed interlopers ("newfags") but tend to stay out of the way of the average user. But that might say more about the "hardiness" of the average user—it takes a certain self-sufficient mindset to function in even controlled anarchy, and this mindset often makes one immune to confidence men.