"Is he just a bully?" I mean, yes, and I say this without any intention of minimizing or justifiying, but: Which of the leaders/founders of firms at that scale

"Is he just a bully?" I mean, yes, and I say this without any intention of minimizing or justifiying, but: Which of the leaders/founders of firms at that scale and success do you imagine do NOT have a history of bullying? A certain amount of what we might call "force of personality" is required to get something off the ground. Once it succeeds, these people live their lives in a place where there is an enormous power and wealth differential between them and everyone around them. Those two factors will absolutely put you at risk for shitty behavior, I suspect.