My guess: expensive real estate, distorted tax rules that make it advantageous to hold a mortgage [1], and availability of very long term mortgages (up to 100 y

My guess: expensive real estate, distorted tax rules that make it advantageous to hold a mortgage [1], and availability of very long term mortgages (up to 100 years). So people take a mortgage and never pay it off, even if they could afford to. Net household savings / debt statistics might tell a different story. [1] Though IIUC the mortgage deduction and its counterpart of taxing the "income" of living in your own house rather than renting are going to be phased out. So this reason would not apply for much longer.