The basic problem is the limestone. Because of the limestone, seawalls are essentially useless as the water goes underneath through the porous ground. I think very likely the comments only seem exaggerated to you because it's difficult to imagine with all the people around you driving fancy cars and buying expensive condos, like pre-cupernican difficult.
No one knows how long miami has, but I would bet it's closer to 20 years than 100 years. To be quite honest, I hope it happens sooner rather than later as maybe something like that will start to wake people the fuck up. Doubtful though. There's always another rationalization.
You're second paragraph is a cruel wish on the lives of millions. You wish this cruelty for the petty purpose of being on the right side of an argument
There is this strange idea, particularly in the US, that we can buy our way out of the problems caused by sea level rise. That's (somewhat) true in some cases, but Miami is not one of them. The ground is simply too porous. You'd have to pull some Dubai-level shit and build a second Miami Beach next to the original and move everyone over.
South Florida will almost undoubtably be the first area in the United States where wealthy people are materially impacted by sea level rise. And because the foundation is so porous it won't take 100 years before areas become untenable. Flooding that last a few days starts to last weeks.
Why would the place you live in have any baring on your knowledge of the effects of sea levels rising? You aren't handed a geotechtonics degree when you move there.
The idea that Miami will be gone in 20 years and not 200 is a ridiculous one. I live here on an island by the sea, I guess that doesn't make me a geotechtonista but it gives me some perspective other people in their basements in middle America might not have.
