I think this is about power and control. The Chinese crypto scene is getting stronger and more wealthy to be controlled. This on a long term might risk the power of the political elites. In addition with a centralized, government-controlled digital currency (which might not be a crypto currency as we know) the government can controll the population and since there is already lots of digital payment systems, they can unify all of them and drive control in to the last unmanaged part of their peoples live.
This is 1984 on steroids.