I was thinking something similar. If a person has the inclination to jump on the bandwagon for any given situation, they are probably actively getting something out of it.
I have a theory that it could have something to do with the haves and the have nots. Whenever some relatively public figure (by default, without critical thinking, is usually labeled as a "have"), slips up in some way, no matter how small, the have nots jump on the opportunity to join a crusade of righteousness where they strike down the goliath for abusing their unfairly acquired power.
It's not necessarily the "have nots" who jump on the bandwagon. Many of these mob inciters are clearly middle class or upper middle class. I've even seen news anchors participate, people who earn several hundreds of thousands a year. In some cases, it may have to do with crab mentality. Wanting to pull someone down who has more than them:
https://en.wikipedia.org/wiki/Crab_mentality
However, if you look at the way James Damore was taken down, or that woman who made a stupid joke at the airport, these people weren't particularly rich compared to their peers. I think that had more to do with wanting to silence dissenting voices and kick someone while they're down, never giving them an opportunity to defend themselves or to have an open discussion.
I agree, it's not necessarily the "have nots" in the typical sense of the term, crab mentality is more accurate. It's just about someone who has more of anything than you - money, power, privilege (loaded term these days), status, etc.
I have a theory that it could have something to do with the haves and the have nots. Whenever some relatively public figure (by default, without critical thinking, is usually labeled as a "have"), slips up in some way, no matter how small, the have nots jump on the opportunity to join a crusade of righteousness where they strike down the goliath for abusing their unfairly acquired power.