Mortgages offered far more people their own house that could have never purchased a house otherwise. Increased demand was met in the majority of the country with increased supply (you may have noticed that houses can be built and the majority of the US is empty). Only a few places on the coasts are so constrained that it pushes people out. The main reason that houses have gotten to be so expensive is because wages stagnated and people don't want to compromise on their demands for space/features (look at the features and size of a new KB home and compare that to the box of shit you got in the 70s). Stripping demand would not make it any cheaper to build houses the way people want.

You can buy a unit in a trailer park on a year or two of low salary. Why do you think people aren't doing that?

If you eliminate mortgages, it only forces people to rent which is a massive waste of money that concentrates wealth into those who are privileged enough to own homes.

WRT wall street, if they were only interested in supporting monopolies, they wouldn't be involved in the IPOs of any company that has a competitor ever. It's not even optimally greedy to only support monopolies because the best returns come from investments in companies that disrupt competition. So you're whole rant against wall street is a bit dumb because it doesn't even line up with the behavior of purely sociopathic greedy actors like you seem to think they all are. Keep ripping down those strawmen.