I mean, he self funded it with something like 180 million dollars. He didnt have to take huge amounts of investors money before that 180 million was worth a shit ton more, and he had launch contracts with NASA to generate income.

So he made it, by building a successful company with his own money and then getting investors to take a small % of his ownership and they were seemingly happy to do it

Edit: really, this is every founders dream. Bringing in investors has so many strings attached and he was able to build something where he could significantly limit that. If you can bootstrap your business you'll be better off in the long run.