For someone who's number one trait is promotion (as you claim), he definitely seems to have achieved much more in his life (I mean, last 15 years) in engineering than most other marketers, promotoers, or, well, engineers.
In what sense? Because the companies he runs do great engineering? Was Steve Ballmer a great engineer because Microsoft built great things? What about Steve Jobs?
Elon Musk is great at a crucial skill for CEOs: selling a vision.
You mean, financing a vision? I don't see many other billionaires doing that (Gates & Buffet excluded).
Do you say that because his wealth is tied up in the companies? Yeah, and Zuckerberg "finances" Facebook, and Larry Ellison "finances" Oracle, and Larry and Sergy "finance" Google...
Tesla has sold vast amounts of equity and debt. That's how the company is financed.