Dave, what does “fault” have to do with anything. Nobody makes a decision on whether to keep bubble priced home based on “fault” of a poor market timing decision, that is ridiculous. If they want to and do not, it is not because of the righteousness of unnecessarily punishing themselves for a poor market timing decision. That would be masochistic and insane. Especially with a family involved. It’s because of exactly what the paper points out. Commercial strategic defaults are not uncommon at all and for some reason people don’t get in the hissy fit about them and place a “moral” component on it nor do the holders of the mortgage place a “fault” component on their decision to walk. It’s a cost benefit analysis based on their individual financial survival and well being. And perfectly socially acceptable which leads into the norm asymmetry and distributional inequalities component of the argument. Different sets of “social” rules for business practices of people and corporations putting people at a disadvantage.