You are lumping the fraudsters with those who acted in good faith together.
Both the lender and the borrower are signing on a loan, the control of the loan is with the lender. They decide if they will lend. They are suppose to check credit, earnings, the true value of the property they are lending for.....they even get to take out default insurance, and they still retain ownership of the property when it defaults. No one holds a gun to the lender.
The lending fed the boom, money was in huge supply and was looking for good returns. The stock market was still in doldrums, so investors went for commodities and real estate ALL AROUND THE WORLD. Lenders like Countrywide were giving loans to anyone with a pulse, this was augmented and evident by the low interest rates. Even the Bush admin pushed for increased mortgage lending. It was people like Brooksley Born who warned Greenspan et al of the out of control derivative market that was funding the mortgage tranches. They, the lenders, the credit agencies...they all had the overview of the market to know things were out of control.....NOT the individual borrower. The individual borrower had no inclining of the size of it. Those regulators did nothing, just as they did nothing when the dotcom boom busted. Bush stripped the SEC to nothing, the FBI was not investigating mortgage fraud even when they had full knowledge of it.
Don't try to shift this blame to individual borrowers, don't try to shift blame to SNAP recipients, those dogs won't hunt.