Chinese people (the ordinary ones, not the rich) have almost nowhere to invest their money somewhat secure because of capital control and hard control of the stock market by the CCP.

Coupled with a culturally ingrained appreciation for real estate, this led to a huge housing boom - it's the only viable investment and there's the expectation that young men own real estate. And this turned into a huge bubble where shoddy, unusable buildings are built in hastily "developed" areas that will never house people.

This bubble was about to burst, but since that could endanger the CCP, they managed to turn that into a rapid deflation instead.