I don't know if he's super smart of mediocre and I think it's hard to judge from afar. But he does seem to make some bad decisions, like:

- The Boring Company - betting on self-driving tech - getting kicked out of Paypal - sleeping on his factory floor - trying to run 3-4 companies at once - SolarCity - claiming he wants to overengineer the tolerances on his cars - an iPad instead of a dashboard

Basically, I just see a lot of his decisions are not well thought out. His main skill seems to be getting people to give him money.