Bill Gates for instance, although his model seems to be give it all away to good causes he believes can accomplish good. Elon still seems to believe more in his own capabilities to accomplish worthwhile things with it.

I expect he too has a little txt file somewhere on his desktop, with various amounts as milestones to unlock the next project.

Maybe at $22 billion he can afford to start asteroid mining and in orbit construction or something that would top his current accomplishments.