I would agree that higher IQ ==
greater potential for success. That's a pretty obvious conclusion.
However, every millionaire boss that I've had in my life was cognitively dumber than a box of rocks. And pretty ignorant of worldly things. But they were narcissistic snobs and somewhat evil. So there's that.

Bosses like to boss people around. That's why they become bosses. Personality plays into that, it probably takes a certain degree of narcissism to get there in the current culture.