Sure, I agree this is not a sustainable practice for most people. I think to go through this and come out sane, "work" must have a different meaning than it does for most people. For the likes of Musk, working seems to be equivalent to being in a mission to change the world. When operating under this mindset, you work not just because what you're doing might lead you to a better socioeconomic situation, but because that is the most interesting & important thing you could possibly be doing, ever. Then "working" (for a lack of a better term) 100+ hours a week is nothing but having the most fun you could possibly have. It's the sense of purpose here that I think plays a major role in turning work into something that can subjectively be more meaningful than the things you mentioned.