Just like in business. Electric cars were pushed by Musk, yes, but they were helped by rapidly increasing battery capacity and demand through the increasing sentiment against ICE cars.
SpaceX is definitely also cool, but by now every billionaire seems to have it's own space company. SpaceX is still pushing for Mars like nobody else, but it's not like the field is deserted.
> I believe Musk is one of the few who has built companies [...] which nobody else would even want to get into because they thought they were not worth doing for making money.
Given how many insanely valued companies we have who's business model is basically to spend VC money (see, for example, Uber), I highly doubt this. There are also a lot of small-time car manufacturers, with quite a few specializing on electric vehicles even. There's definitely money to be made in this space.
> In fact, people like Bill Gates are still shorting Tesla because they don't believe it has value.
There's definitely a way where you can believe both, that a) Tesla really fast-forwarded the adoption of electric vehicles and did something good and b) that Tesla being the most valuable car company on the planet is insane.
I'm not saying Elon achievements are not impressive, they definitely are and his net impact is positive. But just like Einstein, if it wouldn't have been for Elon, there would most likely be another company filling this space right now.