There were several different issues at play there. Being underwater on your mortgage isn’t great but it won’t make the bank repossess it. You have to stop paying your mortgage for that to happen.

That happened in most cases because they had variable rate mortgages. When interest rates skyrocketed, so did people’s monthly payments which made them unable to afford them.

The real lesson for consumers was to never get variable rate loans, always lock in that interest rate, you can always refinance later if interest rates go down