Undeniably Elon’s success is his tremendous wealth, the basis of which are two very valuable companies that the cofounded and has as CEO marketed brilliantly, if not always honestly.
He obviously knows a lot about what people to work with.
It is highly unlikely he knows how to build or design almost anything Spacex or Tesla makes. He knows a lot about everything they make of course, and can get more detailed briefings and information on it that anyone, but he didn’t make it.
So the wealth and the successful companies are his success sure, but his greatest personal accomplishments are obviously his marketing skills.
These were very difficult industries, industries that were extremely contrarian to bet on when he did. Making the financial bet alone would be a great accomplishment for any normal person. Peter Thiel is a famous investor for making far less contrarian and far less successful bets without operating anything except Paypal.
Musk's bets were far more concentrated, and he chose the personnel, operated the companies, made the strategic decisions, and yes, also marketed them brilliantly. But he only got to flex those marketing muscles because he spent a decade assembling, managing, and financing the teams that built the product in the first place.
Perhaps it’s just that his wealth got the better of him.
He has obviously been highly successful at marketing. But his "real success" has been in delivering products like useful electric cars and reusable rockets that didn't previously exist. His marketing skills help with that, but all the marketing in the world isn't going to sell a product that doesn't exist (except in crypto).