And then the sheeple decided it didn't make "financial sense" and walked away. Walk, sheeple, walk.
2008-07-29: America's house price time bomb
In May 2006, at the height of the housing boom, Karen Trainer bought a $500,000 apartment in California - with money borrowed from her bank.
By this year, Karen still owed $500,000 on her mortgage, but her apartment was worth $200,000 less.
So she was deep in negative equity and, to make matters worse, the interest rate on her loan was about to increase.
"I thought 'this is crazy'," Ms Trainer says. "It just does not make financial sense."
As a successful professional, Karen could comfortably have managed the higher mortgage payments her bank demanded.
Instead, she decided to stop her mortgage payments altogether and let her bank repossess her apartment.
Her credit record will be badly damaged by the decision, but Ms Trainer expects this to recover soon.
"Generally speaking, within 5 years you are about back where you were, so my husband and I decided we'll take the hit and live with it."