SpaceX is successful despite of Elon Musk, not because of Elon Musk. SpaceX spends a lot of energy keeping Musks's insanity and emotional outbursts at bay. Tesla has also learned how to manage Musk, though not quite as successfully as SpaceX. Twitter is still figuring it out, but I'm sure that they too will learn how to manage Musk.
I think it's useful to compare Musk with fire. Fire is useful, if controlled. Fire can be very damaging if not controlled. You have to control Musk while giving him the semblance that he's the one in control. Kudos to those who've successfully been able to pull that off.
As I said, fire is useful. Vision is definitely one of Elon's strengths, along with enough knowledge to understand feasibility. Execution doesn't appear to be one of his strengths, but he's made good hires for people who also recognize Elon's strengths and weaknesses and can successfully manage him.
I think it's useful to compare Musk with fire. Fire is useful, if controlled. Fire can be very damaging if not controlled. You have to control Musk while giving him the semblance that he's the one in control. Kudos to those who've successfully been able to pull that off.