> Sounds like a load of bull.

Don't take my word for it. There are plenty of professionals and agencies who explain how it can be done[1]. I'm not saying there aren't tradeoffs, but it is definitely possible.

https://www.nifc.gov/fire-information/fire-prevention-educat...

> how can you make a house resist major fires such as the LA Fires?

Not an expert, but the main ingredients seem to be to create a defensible space free of combustibles (trees, brush, foliage, wood piles, wooden fences, etc.) within a perimeter of the house and build the exterior fire-safe materials (tile, slate, sheet iron, aluminum, brick, or stone).

> Why aren't multimillionaires doing that?

I don't think the wealthy have anymore risk foresight than anyone. Almost everything in the system is discouraged from emphasizing catastrophic risk: buyers want a fancy looking traditional house (not a barren yard and unconventional building materials), real-estate agents want to close on as expensive a property as fast as they can, and the municipality is discouraged by owners/voters from forcing expensive fire-safe changes. It's human nature not to learn hard lessons until they directly affect you.