Prior to the 2008 crash, mortgage lenders didn't care if the borrowers couldn't afford the loans. They made as many subprime loans as they could, then they would sell the loans to Wall Street firms, who would repackage them as mortgage bonds, and then sell them to private investors. This was called the originate and sell model.
I remember the anecdote about the California kid who was working at a car wash one week and making 20 grand a month writing mortgages the next week.