I know a few people that can afford the payment, and will still walk away from thier homes.
For me, I will be staying in my depreciating home, and will not think about what I have gained or lost until my son graduates(10 years). I know right now I am right about even, but I did put down 20%, and therefore that is lost for now.
The ones that are looking to walk, and can afford the payment, are not happy with thier home, or neighbors, or area etc.
