I agree with your analysis of how insurance works. But, wouldn’t the burden of calamities only spread amongst the insurance holders? I am not sure what the factors are, but if a lot more people go without insurance (because they are independently wealthy or live in an uninsurable location), doesn’t change the calculation?

People who go without insurance because they live in an uninsurable location would leave those who remain insured better off, because the insurance company would be less likely to need to make an exorbitant payout to the victims in the disaster-prone area. This is of course true as long as insurers don't manipulate the market to keep premiums high despite their total expected claim outlay lowering.

As an insurance buyer, in a hypothetically ideal market situation, you would want all those who also purchase from the same insurer to have the lowest risk of needing an expensive claim paid. The lower the expected payout * risk of disaster means lower premiums for the insurer to still make an expected profit.

I think what will happen is simply: Houses are built in places which are more insurable, existing danger-prone houses will exist until they are destroyed, until then they will increasingly be status objects for the elite who can afford the loss and have inaccurate risk appraisal. The fact that so many valuable objects are kept in Malibu/Palisades homes despite fires happening there a lot (as recent as 2018) indicates homeowners in disaster-prone areas aren't acting perfectly rationally.