There have been bubbles in the housing market in the past - houses are quite useful. It's a bubble if the valuation is inflated beyond a level compared to a re

There have been bubbles in the housing market in the past - houses are quite useful. It's a bubble if the valuation is inflated beyond a level compared to a reasonable expected future value. Usefulness isn't part of that. The important bit is 'reasonable', which is also the subjective bit.