Feel free to giggle and roll your eyes whenever you read about billionaires building secret bunkers with a plan to hole up if/when the world falls apart. Nothing is sillier than a secret bunker. And the fact that they take these bunkers very seriously makes them even more laughable. The moment the world becomes so bad that a billionaire would be willing to move into a bunker, is the same moment the billionaire becomes just as poor as anybody else and would have no way to maintain or defend their bunker.
If a billionaire is willing to abandon the very long list of every luxury and convenience they experience on a daily basis, then we can assume we’ve arrived at a dystopian future where core systems like electricity and water have failed, where the internet no longer functions, and where the financial system is no more. In this scenario, dollars would be meaningless, and billionaires would no longer exist.