We people don't have exat idea only china is controlling bitcoin, but through some blog most of the bitcoin farm are with them, because china biggest bitcoin farm.If they dump all their bitcoin in one shot we will see more price dump.BTC
having big mining farms doesn't mean Chinese people have the most amount of bitcoin. besides your last sentence doesn't even makes sense, you say Chinese have the biggest bitcoin farms which means the have heavily invested in bitcoin then you say if they dump all their bitcoin in one shot we see price dump, here is the problem, they are making profit with bitcoin and the higher the price the more they make so why would they want to dump?!
besides US had more than 51% of hashrate at some point in the past (GHASH.IO) and nobody seemed to think US is controlling bitcoin! so why now.