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.
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.