The previous poster was comparing building California homes near trees to the folks who build on flood plains.
A natural expansion of that tells you that you can't build in Santa Rosa (Tubbs Fire), Oakland hills (more fires), the Bay Area (earthquakes, someday the Hayward Fault will let loose), or really much of anywhere near the coast (rising sea levels, California Coastal Commission has decided that protecting your property with water barriers is no bueno).
This isn’t a big deal when property is cheap and can be paid off within 5-10 years, and rebuilt. But housing has become dramatically more expensive relative to cash flow than it has been historically.
With a cheap enough house, it's just the thing. Spend all of your money on land.
Maybe the future is in RVs. If they let me get away with it, I can see scraping a parking pad in Big Sur and sticking a motorhome on it. Relatively earthquake-proof. Fire? Simply drive away. Vacations to the desert can be slept in your own bed. Want to live the classic life? Buy a GMC Motorhome.
Maybe those behemoths make sense. Live the Jim Rockford lifestyle.