If you're a billionaire or close to it, the US healthcare system is fantastic, unless of course you're traveling in one of the "medical deserts" and have an acute emergency.
A billion is just three Manhattan skyscrapers, so it can't change a city. Depending on where you live, you might well experience the exhaust, dust and noise of these environments, no matter how luxurious your individual dwelling.
But I did double-take when walking past Russell T Davis (or a lookalike) in Sheffield a decade and a half ago, and Richard Osman in Cambridge train station some other time.
I'm fairly sure most of those can go out for dinner or drinks and no one would know who they were.