The success of SpaceX belongs to Gwynne Shotwell far more than it does Elon. It also doesn't hurt that his CIA buddy joined NASA in time to give SpaceX a $400m investment.
I cannot comment about Gwynne Shotwell; I lack the corresponding knowledge. I can only note that if Elon Musk is a completely mediocre person, he still must be doing something right because the world is full of mediocre people who achieve much less than he has, and I don't believe in blind luck.