Did he really?

Rather is it instead some billionaire would have done it. We had the bad luck of it being Elon Musk instead of someone better.

He put money in Tesla. That is his main contribution. Tesla which kinda had the first mover advantage of being the one well placed EV company via their deals with AC propulsion and Lotus. Both which happened without Elon.

What really made Tesla possible aka the first Tesla roadster possible was Tappering and Eberhard personally flying cross the Atlantic to go personally meet Lotus leadership for Lotus to produce the gliders aka most of the car. The chassis, body, the suspension. The roadster was mostly a Lotus made car in which Tesla dropped electric drive train. Electric drive train, which core technologies were licenses from AC propulsion.

Funnily worlds first big EV company might have been called AC propulsion. They had their Tzero prototype, which is pretty much hand build kit car Tesla Roadster. All of first Eberhard, Tappering and then Musk talked to AC propulsion about them starting serial production of tzero. However it didn't happen since the company leadership adamantly refused. That is why Eberhard and Tappering incorporated Tesla Inc. They needed separate company to start production of tzero style roadster, since AC Propulsion strictly stuck to the field of just electric drivetrain tech. Under which field they then did what they thought their business is, AC propulsion licenses the drivetrain tech to Tesla and then let Tesla take the job and risk of actual automotive production.

Main contribution of Elon was insisting on carbon fiber instead of glass fiber composites. Requiring expensive retooling at Lotus for the Tesla production line thus making making car more expensive and saving negligible amounts of weight.

All the engineers apparently went: We already considered carbon fiber anyway. Carbon Not worth the extra cost of parts for the weight saving. This body can be perfectly well be done with glass fiber composites. Like you are the main stock holder, so it's your money. We do it in carbon fiber, if you insist. Just saying there is no reason to do it engineering wise.

However Elon wanted cool space age carbon fiber body so they did it in carbon fiber. Again at great extra cost for both Tesla and the customers.

Sound familiar? Elon insisting on non practical engineering choice, since he got in its head a obsession to make the thing that way and no otherway. Like removing radars and other sensors even though as leaks have later revealed all the main engineers on the driving systemics said it is stupid idea and leads to unreliable sensorial leading to problems.

Atleast in the camera only case he is trying to save money. I guess that is improvement over the unnecessary exorbitantly expensive carbon body paneling on the Roadster (Roadster is aluminium tub chassis car , the carbon fiber was doing no mechanical work, it was literally just body cladding).