Building out of wood is cheap and perfectly strong for most areas.

Engineering is always a set of trade-offs.

Given the choice between earthquake-proof and fire-proof I'd go with earthquake-proof every single time since you can't run from an earthquake.

I don't get how can one put his own future in a cheaply built building you're one fire or thougher-than-usual natural event away from losing.

It's normal nobody wants to insure such risky assets, especially as nominal value of this wooden crap is stellar due to the skewed demand/offer ratio plaguing good parts of US.

In my life I've seen my and my family's real estate being hit by a tree, fire, floodings and I've never had to face anything close to a total loss.

Huge expenses? Sure. But never anything close to a loss.

The only thing that could put my real estate on a serious risk are earthquakes, I guess that's a scenario where lighter built houses would have instead an advantage.

It's mostly that there is virtually no one in America who knows how to build with concrete/bricks.