"she doesn't need the money, she is one of the richest women in the world."
Never underestimate what the rich and super rich will do to get more money.
Does Warran Buffet need more money? Yet he's still trying to make himself richer.
Do all the top CEO's, VCs, and board members in the world "need" more millions and billions? Maybe not. But it hasn't stopped them from trying to further enrich themselves.
Besides, there could be other motivations for this stunt, such as fame or wanting to be talked about or thought of as a certain type of author.