The mortgages that banks make have risks associated with them. That's why they charge an interest rate, that they themselves set. No one forces them to give out loans. Now, if the government mandated an artificially low interest rate in return for homeowners promising not to walk away from mortgages, that's be a whole other matter. The banks aren't innocent victims. When they write the mortage, they access and take on the risk and the reward.

Also, businesses do this all the time.