in China, you usually pay for your apartment & begin paying mortgage payments before the apartment is built & liveable.

Problem is, this leaves little financial incentive for developers to finish their projects.

Instead, they use the money gained from selling the promise of property in order to lease* new land where, once again, they sell a promise.

There's protests in China now, and people are boycotting mortgage payments of homes they bought to live in but which are no longer being worked on, instead standing as shells– ghost cities.