I am nowhere near the financial situation as some of these people are and I’ve prepared for fire and tornadoes. If I lived there and had their kind of money, I’d build to resist fire and have backup if fire or security were not available.
Southern California foothills (where many of these wealthy folks live) are prone to severe fires every now and then.
Mother nature is going to win the battle.
I suppose you could build an underground concrete fire-proof bunker and store valuables there—but barring that you are on your own.