"I can't think of anything interesting to do" is very different than "there is nothing interesting left to do."
I will grant you "the trappings of wealth" would seem to be boring in short order. How many "exclusive resorts" can you stay in until all the ultra-master-upgrade-penthouse suites look the same? How long can you listen to the "in crowd" go on about their money and faux-philanthropy?
Bill Gates is a perfect example here. Made his money, changed the world, checked out, made a difference. Do you think Bill is bored?