Why the ” ” around invest? That’s probably the best way to use equity.
I myself have used the equity to buy other properties, both in San Diego and in other locations not in California.
I know others who have used their equity to buy out their credit card debt and pay for medical bills. Yes, they will still have to pay it off, but at least they can use it to manage their debt.
As for why does a house (and all real estate for that matter) generally appreciate in price versus other assets, that is the value of real estate. It is a terrific vehicle for creating wealth.