I’m not totally sure about it being all Giannis, or Dame for that matter. Let’s not overlook the fact that Terry Stotts was hired to be Griffin’s lead assistant and quit during the pre-season because of how Griffin treated him. Griffin might have been one of those guys that no one likes working for, one of those insecure bosses always looking over their shoulder and yelling at everyone all the time. They exist in every profession, and they suck the energy out of everyone. If you’ve had one, you know what I’m talking about.
From my personal experience, I always thought it could go either way.
I definitely know of guys like the one's you described.
But I also know of guys who constantly undercut their boss, overstep their bounds, have trouble taking a subservient role after being in charge in the past, etc.
I wouldn't be surprised to learn either one was true, but of course with the Griffin firing now, it makes me lean more towards Griffin being like what you described (insecure dictator).