Why do Bernie's supporters blame banks for crashing the economy?

Shouldn't the millions of people who bought and flipped houses they couldn't afford using shady mortgages accept some responsibility?

Nobody made them live beyond their means, then default on their interest-only mortgages when they couldn't flip their houses at a profit 5 years later to get a new shady mortgage.

Who would have thought that people with no money would eventually default on several hundred thousand dollar mortgages? I'm shocked.

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