The size of the BTC network is a huge part of its value. It's already hard even for state actors to compromise the blockchain.
One can imagine the ability of China to mobilize capital infrastructure to dominate mining space, especially when they're manufacturing all the bitcoin ASIC hardware.
It seemed like there were grave concerns once ASIC hardware hit BTC, locking normal people out and introducing an attack vector disproportionately favoring existing capital to take over the network.