People buy houses by taking loans with high interest. Next year, the house they own increase in valuation equal to the amount they paid interest.

House owner is happy - their asset has increased in value. Bank is happy. They got the money. City is happy. They got their taxes for the higher valuation of the house.

After sometime, The middle-class becomes lower class and moves to rent. The lower class becomes homeless as they cannot afford the rent.

The cycle repeats.