Not necessarily true because you are covering your need for housing at the same time as paying the mortgage. So even if it appreciated exactly at the same speed as inflation(as one would expect if housing prices were flat) you are only paying the interest rate but gaining an asset at the end of the mortgage. Also, that asset theoretically allows you to cover your housing needs for the rest of your life(with appropriate maintenance), so it should be valued as potential sale price + the value of owner's equivalent rent for the rest of your natural life.