Part 1 investigates how banks were unregulated and were giving loans to those who could not afford it, as well as engaging in practices that were just outright illegal.
The important thing about this documentary is that it helps connect the personal story of easy loans with the larger story of weak oversight. It was not just one bad borrower or one careless bank. It was a whole chain of incentives that made dangerous behavior look profitable for far too long.
When people could get loans they did not understand, and institutions could package those loans into products that seemed safe, the risk did not disappear. It simply moved around until almost everyone had a reason not to look too closely. That is why the crash felt sudden to the public, even though the warning signs were building for years.