I don't. People who don't leave encourage abusive bosses.
When large part of your team quits, it will be a painful but efficient lesson. When they don't, it sends a signal that wrong behavior is okay.
That's same as not reporting rapes or turning blind eye on "inconvenient" crime. It really really encourages crime in my opinion.
There's some amazing detail in the court documents from his 5 years of multiple lawsuits against our former employer, including him assaulting the videographer at a deposition and being removed by the police. Again.
I didn't leave because I was worried I'd never get another job and no one would believe me. After all, what are you supposed to do in an interview when asked why you're leaving after 3 or 4 months? Do you really want to tell a potential employer you're leaving because your boss is verbally abusive and slapped the back of your head because he thought you were being stupid? I worried -- and I think it's true -- that I could easily be written off as whiny or entitled or difficult or even just too much trouble to deal with. I also had just left school and couldn't really afford to repay the relocation bonus they gave me (protip: always write into your contact that repayment is prorated over the first year of employment. And remember relo bonuses are taxed when you decide how much to ask for. oops on both counts.)
It's hard.
Now I'm mature enough, and have a string of successful jobs behind me plus savings, that I can joke about it. And if anyone doubts what working with him was like, pull out the description of the deposition that lead to him being declared a vexatious litigant.