I guarantee that those mentioned (Elon / Buffett / Waltons) have employees. I know a few millionaires in the 9 figure area. Every one of them has executive assistants that handle alot of the minutia that occurs in their lives. Even beyond work-related assistants, all of them also have multiple properties and those each have "house managers" that take care of all the catering / decorating / invitations /details for when said millionaire wants to throw a super-bowl party., etc.
Elon Musk aint driving his own yacht.
(For the record, I don't actually agree with this concept, it was just my wife's belief that I am throwing out there for discussion).