Musk was worth ~$300M when he started SpaceX and Tesla, and he bet nearly all of that money on SpaceX and Tesla, and that's why he's a billionaire. His big share of SpaceX makes up like half of his wealth, so from today's perspective he's not putting his wealth into a vision, he's wealthy because of that vision. That's different from Bezos, who made his big money from Amazon and then started putting billions into Blue Origin (which was rather inspired by SpaceX success). That said, Blue Origin was actually founded before SpaceX, but they were very slowly working on their suborbital rocket for a decade before Bezos gave them big cash, while SpaceX started sending satellites to space and supplying the ISS in that time. SpaceX has made 500+ orbital flights so far, while Blue Origin just one.