According to the this chart from Calculated Risk 55% of homeowners in Nevada owe more on their house than it’s worth.
Somewhere I’ve read that 20-30% of homeowners do not have a mortgage, so it’s not this many homeowners who are upside down on their home. Still, it’s a lot of people! And what happened in Nevada? It looks like people walked out of the casino and into the realtors office in the same “double down” state of mind.