He started both Tesla and SpaceX when he had "only" a few hundred million to his name and no more connections than would be expected of a Silicon Valley guy making payment software. And lots of brilliant guys, including John Carmack for instance, have tried their hand at aerospace - and failed. Jeff Bezos started Blue Origin before SpaceX was even founded, and it was literally only last month that they finally managed to get a rocket into orbit for the first time. There's a joke in the industry: 'How do you become a millionaire in the aerospace industry? Start out as a billionaire in the aerospace industry!'
And we live in a world of millions of millionaires, and thousands of billionaires. For that matter, even China is trying their hardest to replicate SpaceX tech given all the resources of the world's largest economy, and 1.4 billion people (meaning a proportionally larger chunk of intellectual outliers), and defacto authoritarian power to make it all happen. Yet they remain (in terms of rocket technology) behind SpaceX.
Being the most successful out of three or even a dozen doesn't make someone exceptional. Because so few people with interest in space have "only" a few hundred million, we can't really say if it's actually his talent that made it possible or simply the result of having access to resources that the vast majority of people could never dream of.
The U.S. has a long history of aerospace innovation, from NASA to private contractors, and Musk was able to use this ecosystem. China doesn't have that.
WEF cites a global space economy at $630 billion, alongside investments of $70 billion. [1] And as anybody with half a head on their shoulder can see, space will be where the big future economic growth will come from. Even if somebody has 0 interest in space, which I think is very few people, that's where the next 'big boom' in economics will come from. And SpaceX was started on a fraction of $0.3 billion with Carmack and Bezos just being a couple of names people on here would be familiar with, amongst tens of thousands. Yet no competitor is anywhere to be found.
And the US doesn't have a long history of aerospace innovation. In 1962 Kennedy gave his 'to the Moon' speech, 7 years later in 1969 we'd go from having nothing to putting a man on the Moon. From 1969 (well 1972 in particular) to the birth of SpaceX (early 2000s) US space technology not only stagnated but regressed. This is why Boeing (who was a major part of the original space race) can't manage to even begin to replicate what we achieved in the 60s, in 7 years no less!
Incidentally this is also a big part of what motivated Elon to start SpaceX. He was looking at NASA's future plans for human spaceflight and they were basically nonexistent. So he wanted to launch a greenhouse to Mars and stream it growing, to inspire people and hopefully get things moving in the right direction again. NASA wasn't interested in any such things, the Russians wanted too much $$$, and so SpaceX was born.
When Musk 'joined' Tesla it was a name and two other guys. The latter two of whom left the company before a single car had been produced. They then sued for the right to be called founders a couple of years after they left, and once it became clear the company would stand a reasonable chance of success.
If my memory serves me correctly, they had put some Sony Handicam batteries on a chasis and driven it around before Musk. Musk was there for every actual product and its development.
And we live in a world of millions of millionaires, and thousands of billionaires. For that matter, even China is trying their hardest to replicate SpaceX tech given all the resources of the world's largest economy, and 1.4 billion people (meaning a proportionally larger chunk of intellectual outliers), and defacto authoritarian power to make it all happen. Yet they remain (in terms of rocket technology) behind SpaceX.