Apparently Miami is a great choice, it even fits the rising sea levels theme. So, in my take, Trump &co messups cause difficulties in budget, so the government won't invest as much as they should in saving the city enough. But they also won't sell to billionaires cuz they wanna hog ownership obviously. So instead, a billionaire will slowly buy individual pieces of land from the building owners that don't wanna stay here longer. Then he'll slowly make a micro city within the city, that expands as he buys back land, but without ever owning the city. It's essentially just like a big company city, inside a real city. It's got its own subset of rules as part of the company terms, but it still abides by the above laws. So the president never has to cede ownership, but also he kinda does practically, but still has the power to throw tantrums and pressure the billionaire. Trump & elon being bros would totally go with the plan of being nice enough to let him at least buy back some major amount of land --- Bonus notes, Grok said Miami is a hotpot of tech startups, so decently rich people, they could afford rent, but still would have to bend to the billionaire's rules cuz they're not on the same tier. Tbh, no other billionaires would move here cuz that would be weird for them to depend on another billionaire.