> If you had that ability, investing in another asset at the same leverage level (such as shares) would net you even more financial income (obviously, its higher risk).

This sounds like Reddit "live in your Mom's basement to save on rent" type financial advice. It doesn't work if you have to use that money to pay rent. Rents tend to be about the same or more than a mortgage. If you happen to live in an area where rents are considerably lower than a mortgage than this is an outside possibility, but this also depends on your rents not skyrocketing over the course of 30 years. One of the great things about 30 year fixed loans is that they allow you to ride out market insanity.

This is the dirty little secret of these housing bubbles. It's mostly the poor who get seriously burned, because people with money have mortgages. They don't have to find a way to pay a rent that increased 40% this year. In fact many of the people are the landlords who are enjoying a massive windfall thanks to the housing crisis. They have an incentive to make sure it continues.