More wealth isn’t enough to satiate his ego, he absolutely craves legacy. As of now he’ll still be a small footnote in history, kids will likely learn about Henry Ford 150 years from now but Musk isn’t worth much of an appearance. Tesla is just an iterative step in EV / battery manufacturing, and is likely to be dwarfed by competition over the next 50 years, even if it does really well.

SpaceX gives him the chance to truly make history. People will learn about our first manned trip to Mars and the first colony. Perhaps even for thousands of years.

Because all their profits come from NASA and starlink… so building a mars capable vehicle doesn’t really make sense from the profit motive perspective. It won’t be profitable in his lifetime.