China's largest number of users and miners, but not on behalf of China to control bitcoin. No one can control bitcoin, like an economic form, who can grasp the route of economic development.
Yes, no one can grasp the route of economic development but through some act and balance some level of things economic development can be control. That's how is goes concern bitcoin either and that's the reason why China control bitcoin.
The fact that China has a large number of miners and users is not something negative, in my opinion. In fact this is something that can contribute for the ecosystem to expand more quickly. Such a populous nation adopting a new currency will make people wake up to it, to the potential in Bitcoin.
You're right mate and this is one of reason why China control bitcoin. Though, China been a nation with high number of miners affect individual miner but China make individual miner think outside the box and they also make them use an updated software.