Let’s say you bought a house at the top of the market and a subsequent market crash left you with substantial negative equity.
There’s no recourse against your other assets if you walk. You haven’t got many other assets, anyway.
All you lose is your credit rating.
What good is credit for?
As far as I can tell, the only thing credit is really any good for is a mortgage. The rest you can save for pretty easily. And maybe you should be living your life that way, anyway.
Remember that borrowing includes tail risk of a Kafkaesque lack of control. Trouble likes company.
I’d probably chuck the keys.