> But if they build tons, the older stock drops in value.
Maybe I wasn’t clear.
The local builders are at capacity. They literally can’t build any more.
> Nobody is paying $500k for a 20 year old house if a brand new one is available for $500k next door.
People are paying $700k for a 70 yo 750 sq ft house in a mediocre neighborhood, and $1m+ for a 50 yo 1000+ sq fr house.
New houses start at $1.5m and quickly go up from there.
Most of the new housing is not in the most desirable neighborhoods (there is no space to build new SFH housing in there), so the houses in the better, established neighborhoods are holding their prices. Note that the prices might be lower than the new houses (sometimes), but they are not going down.
A result of this, using your example, is that there are rarely comparable old and new houses at similar prices.