Elon Musk has 6 kids! He already had enough money to live the rest of his life without lifting a finger over 16 years ago.
Why he is still working 120 hours per week would be a great topic for a philosophical discussion. Who is to say what is considered a good life to live?
I think he is now devoted to accomplishing noble goals that improve humanity since his monetary goals have already been met years ago.
I imagine that once people get rich they yearn to find new goals in life.