The danger, of course, is ultimately to the lender as well as the borrower. I recall the number of S&L's that went under back in the early '90's due to foreclosures and defaults. It will happen again. It will likely be worse this time, as lenders have lowered mortgage qualification standards to include many people who simply cannot afford to own a home at these prices.
This whole process seems to be one of forego future gains for present gratification