[zzapplezz]

The answer is because a resource is at play that is finite: land.

If all the productive land in an urban area is effectively owned by foreign investors and left to sit, then renters bid up the remaining dwellings until they're priced out of the area. It also becomes more expensive to build in that area so the housing stock can't keep up with demand. It's terrible to let a vital commodity lay to waste.

[conanbatt]

housing is not finite

[zzapplezz]

With enough zoning it absolutely is, not to mention the lead time required to permit and actually build it. Once built depreciation kicks in - housing isn't permanent. It's a consumable.