The next stage in climate denialism is climate nihilism: thinking that it's too late now to do anything to directly confront the problem so why bother. All it does is protect and entrench existing extractive interests. We can accomplish amazing things (landing on the moon, overthrowing the nazis and winning WW2) when we align our society and focus the right incentives.
Anything we do to adapt along the margins won't mitigate the next great mass of people opening the spigot on high carbon lifestyles. Political systems will buckle under the weight of human migration away from the vulnerable coasts and once-fertile land now too chaotic to farm. We need to fund and develop the next wave of low-carbon tech to make it good enough and cheap enough to satisfy people's needs now, not piddle around looking for ways to monetize the fall.
"up to 630 M people live on land below projected annual flood levels for 2100, and up to 340 M for mid-century, versus roughly 250 M at present"
250 million people already live in those annually flooded regions, so that's only another 400 million by the year 2100. You think political systems can't cope? China has 300 million migrant workers, most of whom re-migrate every year!! They're coping already. We just need a lot of trains.