It isn’t the amount of time it takes to pay off the house. It is the time it takes not to loose money on selling a house. The number was about 5 years when I purchased my home. You take the selling price of your home subtract the mortgage, taxes, and realtor fees. It now takes 13 years before you can sell your house and break even. This just makes investing in homes worse. It also makes buying a home more risky and inflexible.