I dont think China is controlling bitcoins. Bitcoins is a fee online cyptocurrency and it must not be controlled by any country.
Is a fee online? What a sense for that? bitcoin isn't a fee but it's currency. And it was being possible for some parties will be controlling bitcoin about use 51% possibilities. And again it can get control by some parties.
No fact nobody controls bitcoin. If there is some cons of the control it's going from the creator Satoshi Nakomoto and bitcoin miners. I can understand control from China only in such sense that it's number one by the number of bitcoin users and this is it.
https://blockchain.info/id/pools/It was making sense about Chinese was holding the 51% power right now(hash). It's not only about the bitcoiner populations in such country.