system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we still have to purchase mortgage insurance when it did nothing to stop the mortgage crisis of 2007?
gpt
Because after the mortgage crisis of 2007, the only groups financing mortgages in any volume (Freddie, Fannie, FHA, VA) require it if the buyer doesn't have 20% down.  

One of the problems during the crisis was that several mortgage insurers also failed, leading them to reduce their payments to the above agencies furthering their losses.