Agree CAR but wonder if there is one more factor you overlooked – that high end homeowners often have funds stashed in various places that they can use to feed their home loan during the down economy (a luxury that low end homebuyers didn’t have as they were barely making it to begin with, so any hiccup in their income stream forced them to miss payments).
One theory is that those stashed funds are now becoming very depleted or the high end homeowners have grown tired of watching their life savings go up in smoke so they have decided to start bailing.
I think it is very plausible, especially on the high end homes originally bought with exotic loans.