The author is correct about one of the roots of the problem.
Financial geniuses took this root, manageable even if all of them defaulted, and sliced and diced the bad mortgages into derivatives and managed to inflate the damage by between 1 and 2 orders of magnitude. Then a lot of them walked away with a bunch of money.
The government is involved, but the financial geniuses we’ve idolized for the last 10 or 15 years are a great deal more responsible.
I wonder why the author didn’t include Fannie and Freddie in this very excellent discussion. As I understand it, the big banks didn’t hold these bad mortgages for long - Big F&F guaranteed it all just to keep the $$$$$$$$$$$$$ flowing.