This is the situation in other countries as well. The real estate bubble is about to burst across the world.
They have to. Who else will instead of them. They plan whole economy, not just infrastructure as is in most of countries.
I live in Europe and there are similar situations, well not whole cities, but there are lots of unsold apartments. Our national bank got this apartments for the loans they gave to now bankrupted construction companies.
But reason why those apartments was not sold is simple, they are not the ones customers use. or are to big or o small or poorly made or nto energetic well build. When they were constructed, everything that was build was immediately sold. and Construction business grew 20% or more per year so as worth of square meter. After 2009 things changed.