Inflation must be kept in check or bad things happen.
Maybe the current levels are sustainable. But not all increases in deficit are sustainable.
At some point, particularly given the last 40 years of evidence to the contrary, people need to simply accept that monetary expansion does not "cause" inflation [1]. Inflation is not a monetary phenomenon at all. Inflation is a price level [2] phenomenon largely driven by trade imbalances. Inflation is about market power, or what some call pricing power. The common case here, btw, is when your external partners from whom you need to import critical goods get even a little bit pricing power then you will get inflation. China is seeking to own all its externals and deliberately suppress any such pricing power not driven by its own banks.
[1] https://www.bloomberg.com/news/articles/2018-03-22/the-great...
From where I sit, the past 40 year have shown that, if you grow the money supply only a little bit faster than the real economy grows, then you only get a little bit of inflation.
It still requires them to get many other rich countries to generally buy into their story.
Where do you think your iPhone is built?
I mean, I suppose they can all imagine that spherical cows exist, but wishing won't make it so.
The only real risk here currency revulsion. At some point there is a risk that nobody will want the currency. But the risk of internal revulsion is low. Chinese citizens have to pay taxes and many other kinds of fees and fines in the currency. They have no choice. External revulsion is a threat but here again the Chinese have opted to buy out their external dependencies. This is why China wants to own all that farmland in Brazil. It never wants to find itself in a situation where it must buy dollars in order to buy soybeans and other critical food stuffs.
People will go on and on about China's sovereign debt. They just don't get it. This is basic MMT (modern monetary theory). The bigger risk for China is that they grow too slowly not that they grow too fast.