There are already a lot of places in the US where you can’t get a mortgage. In high rise condos, especially, a lender will want to look at the financial situation of the association. Make sure it is holding enough reserves, etc. If those numbers don’t meet their standards, no mortgage for you. Note that each lender has different standards and different ways to do math!

This has been the case for decades. There are probably a few dozen (or more) buildings like this in every large city.

And life goes on. Nobody will come rescue you from financial loss.

Edit - also keep in mind that these situations aren’t permanent. These cash buyers stand to profit if they buy low, fix things to the point that mortgages are possible again, and then sell. In a wildfire zone, that could mean that a group buys up many homes in the same area for cheap, tears some down to make buffers, modifies others for resiliency, etc. who knows