People moving into areas of high risk are only a tiny portion of the problem. The existing owners, and their kids, are already too much risk for a lot of places. Hundreds of thousands of retiree’s already live in beach front condos that have been there for 30 years or more, and they have no way to move. There are millions more in similar places, that just have to accept whatever happens to them, because they have no resources to move, and a fixed or non existent income.
That problem is going to be the biggest one when dealing with climate change as a species. Moving hundreds of millions of people, who can’t afford to move, to places that don’t want them to move there. Interspersed with random natural catastrophes causing horrible loss of lives and resources.