"And their time frame is what, five years? How do you reconcile those two things: It’s a 100-year problem and a five-year investment cycle." The answer is simply that the private equity firm does not account for the long term, but that the city of Miami Beach will have to—soon.
And that is fundamentally what makes climate change so difficult to deal with. The economic incentives, which only really look 5-10-15 years out, can't respond to consequences that are 50-100 years out, and by then it's really too late.