This certainly goes against a big part of the media narrative (both left and right) about defaults. The leftwing coverage focused more on predatory lending while the right focused more on demonizing Freddie/Fannie. This study is looking more at actual defaults rather than being underwater.
Plus, let’s face it, it’s much easier to downgrade from a 1.5m home to a 800k home than it is to go from 500k to 300k. Lot of “want” vs. “need”.