2. The mortgage meltdown started with subprime loans, which were not guaranteed by Fannie and Freddie. It was private lenders selling loans to clients and then selling the mortgage-backed securities on the private investor market.
3. Fannie and Freddie were not under federal conservatorship at the time. They were regulated by the government as government sponsored entities (GSE) but were corporations with shareholders and profit motive. The regulation under the Bush administration was extremely lax. There was no FHFA or CFPB.
4. The real damage happened between 2001-2006. That's when option ARMs, pick-a-pay loans, and NINA/SISA (no documentation) loans were being made. The fact that these loans would age poorly was well understood in the industry. It was just assumed that continually rising property values would offset how genuinely terrible these loans were.
5. After the clusterfuck, Fannie and Freddie were brought into conservatorship by the federal government to prevent a repeat, and it has largely worked. The quality of mortgage paper is much, much higher than it was 20 years ago.
Yes, it was 100% stupid greed. And to be clear, nobody learned the lesson. The Trump administration is going to defang CFPB and probably bring Fannie and Freddie out of conservatorship. Another mortgage meltdown is a predictable outcome of this and I would expect it around 2032.