> it's my home, not an investment

Oh great! I'll take one of those. Maybe two. Where do I sign up?

> If the value then drops 10x, you won’t get your property tax refunded.

That's right. And why would it?

But also: your example is imaginary. When was the last time that house values dropped 10x or even 5x? It's counterproductive to make tax policy based on the extreme cases that have never happened.

In a lot of places, if not most, property taxes are based on the assessed "current market value" of your house and audited annually, which can change a lot from year to year. Property taxes are paid annually, not when the house sells. If the house goes up 10x in a year, the property tax also rises which makes it very hard on a fixed income when you're retired, especially when the gov't artificially calculates inflation at a lower rate so they don't have to pay as much in social security benefits to those seniors reducing their purchasing power over time.