As mentioned elsewhere in the thread, you are not short some dollar value but short some "survivalship house value" based upon your own subjective tolerance for

As mentioned elsewhere in the thread, you are not short some dollar value but short some "survivalship house value" based upon your own subjective tolerance for what is a "minimally viable living situation." If you live in the bay area, you may be short the "house value" equivalent of $500k, but living in Illinois you may be short the "house value" equivalent of $250k. Of course the location is part of the "minimally viable" part for certain people, but for others this is a less important part of "viability". Regardless, it's not a dollar value, it's "house living value", and anything beyond that part of the equity in the house you own (for most people: the majority of it) is speculation/investment into the real estate market.