Why are people like this, and why are so many of them on this platform?
It seems like it would be so exhausting with little to no benefit. Then again, some people just thrive on chaos and drama to the point where if there's not enough naturally existing, they create it. It's basically like sex or hardcore drugs for them. How do you get people to stop liking sex and drugs when bans are basically the equivalent of giving them a buzz and an orgasm all at once?
As for why so many are on the platform, I have a theory: They get banned from the other places. Eventually the barrier on ban evasions gets beyond their pay grade, so they fuck off elsewhere for a bit to sow chaos in new territory. Seems like a majority of the people who organically share their Fediverse origin story are along the lines of either "I left Reddit because Reddit did X" (ex: API ban) or "I got permabanned from Reddit because I said puppies are cute" -- and let me tell you, if you go and look at the puppies are cute user's Fediverse profile, more often than not, you'll quickly start to realize why another platform might've had motivation to shoo them off.