Then why is Musk (and Bezos with Blue Origin) the only ones who have done so? There are a lot of people who have more money than Musk had when he founded SpaceX and Tesla.
I’d argue that opening up a new frontier for society’s restless (space) to relieve the pressure that’s been mounting from the lack of any kind of frontier is as important as anything else. If we keep ignoring that pressure it’s eventually going to have massive destabilizing effects… in fact, I think we’re seeing some of that already.
Look at Bill Gates. He could certainly build rockets, but he'd rather help people solve other, arguably more important, problems.
Or Larry Ellison. He'd rather go race boats and play with swords.