It is a fact that mining power is mostly based in china. And there are so many bitcoin adopters there. But i don't think they totally control the bitcoin. They only have enough impact.
Although we know China is the farmland for bitcoin mining but that's information from years ago, with a market where mining has become more difficult, farms in China are decreasing, only a handful of large farms still exist, the percentage of bitcoin that China can hold right now is quite low for control. Besides, we should not forget that the policies prohibiting mining and using bitcoin in China, it has little or much influence on investors here, resources are not enough for China to control the whole market is becoming more giant