The California (and Florida) situation is easily explainable [1]. As this video points out you have these forces in play:
1. The state who sets insurance price caps for political expediency, basically to increase house prices (because they'd go down if insurance prices could float freely). BTW we have examples of areas that are uninsurable like the Florida Keys;
2. The homeowners who want their house prices to go up and want to pay as little as possible for home insurance; and
3. Insurance companies who can't write too many policies so they remain solvent. Price caps ultimately lead to insurers leaving the market.
LA in particular has competing problems: wildfires and earthquakes. If you want to avoid total loss due to wildfires, first you wouldn't build in Pacific Palisades at all. It's a vegetation rich area between hills with potentially high winds. If you want to avoid fire loss, you would build out of concrete not timber-framed buildings.
But the problem is that earthquakes have the opposite building priorities. Lumber is actually quite good in earthquake zones because you tend to get less loss of life from the collapse of timber houses.
Now you can build concrete houses that are earthquake-resistant (eg in Japan) but it's expensive.
Ultimately all of this comes down to a malaise brought on by high house prices. Voters consistently vote for policies that increase their house prices with absolutely no concern for the externalities.
If it now costs $1 million to build an "average" house, then you're going to be spending $20,000+ a year on insurance. If your house only cost $100,000, you wouldn't have that problem.
It's even worse in California because a lot of property taxes are capped so the state government can't even recoupe taxes from a lot of high-priced property but they suffer the costs of it (eg by being the insurer of last resort).
[1]: https://www.tiktok.com/t/ZT2Jek6a6/