Your reasoning might hold for an average user but not for a billionaire like Musk. He'll obviously have very smart people research and design a cycle for him that mitigates the usual side effects. With calorie intake monitoring, vitamins and anything you can remotely think of. A guy like Musk will also react more controlled with regard to amphetamines.

Whether he actually uses amphetamines I have no idea. But I'd not be surprised to learn that he has his own RC lab.