There are protections for house owners. In extreme cases, one can walk away from a mortgage, and take a 7-year loan default.
a) If you are 20% down, you still lost 20% + whatever money you put into it. On a million dollar house this is 200k of wealth evaporated.
b) Having no credit for 7 years can be life changing. Not that great to live this life in the US.
