Are you arguing that, because he's rich, he must not have done a good job ? Because that doesn't follow in general either. I think we can all think of a few dozen counter-examples where people got rich while actually putting in a lot of work and risk.

Especially Elon put all his money on the line a few times. And he is definitely not just an idea guy.

I have not seen any real engineers too overwhelmed with his apparent knowledge. Things like claiming that the new Roadster will have pressurized air thrusters that will allow it to hover a few feet off the ground for a few seconds comes to mind.