I'm not certain that assumption is necessarily correct.

Elon Musk seems more focused on affecting meaningful change and driving technology forward. He's using corporations as a vehicle to do that and making money is an incidental side-effect.

If profit was his primary motive, there would have been many other ways to invest his fortune from PayPal which entailed far lower risk and potentially significant gain.

private corporation. Big difference. They also do not plan on going public until their Mars program is established.