Some countries have wealth tax. Some countries don't.
It's sensible to park your money somewhere, where it's not taxed.
If you build more of it, yes, you will meet some of the housing demand (basically just for the richest), but housing is competing with rich people saving.
You need to tax unproductive behavior to rid of it.
Edit: or even if there is a prospect of this being the case.
They have also put heavy restrictions on bank lending.
Basically they are desperately trying to slow/reverse responsibly an out of control housing bubble.
That said they have unique cultural and geographical issues in terms of the sheer scale of their urbanisation
In addition, how do you account for the massive drop in new development that occurs as much fewer new houses are built as the housing prices are being deflated due to investment being banned? What about apartment buildings?
All genuine questions I would be interested in hearing a solution too?