Says who? China and Hong Kong are different, China completely ban Bitcoin while Hong Kong accepts Bitcoin.
SHANGHAI/LONDON, Sept 24 (Reuters) - China's most powerful regulators on Friday intensified a crackdown on cryptocurrencies with a blanket ban on all crypto transactions and mining, hitting bitcoin and other major coins and pressuring crypto and blockchain-related stocks.
Ten agencies, including the central bank, financial, securities and foreign exchange regulators, vowed to work together to root out "illegal" cryptocurrency activity, the first time the Beijing-based regulators have joined forces to explicitly ban all cryptocurrency-related activity.
That story is old, and it's outdated:
https://www.coindesk.com/consensus-magazine/2024/02/05/china-never-completely-banned-crypto/Binance is doing $90B per month in crypto trading in China, so it's not "banned" by any normal definition. Individuals can still buy, sell and hold Bitcoin in China.
As of last September, China had 21% of the world-wide hashrate for Bitcoin:
https://buybitcoinworldwide.com/mining/by-country/So that "ban" isn't really doing very much for that either.
Regardless, whether China did or didn't fully ban Bitcoin on their own soil isn't really the point of this thread. It was discuss the possibility of a country like China having the ability to take over Bitcoin. The answer here seems to be: yes, they technically could, but it's unclear what they would gain from doing so, so in lieu of a strong motive, it's unlikely to happen.
No matter what facts you include here. A nation cannot control Bitcoins. It’s designed in such a manner that no one can have manageable access on it. Yes nations can track the transactions made with Bitcoins. They can impose a tax on it, but there is no way possible they can control it. China always promises things with high values but never able to prove it or delivers it. Hence its not at all possible.
Any entity that controls 51% of the hashrate controls Bitcoin, and while that has never yet happened, it's certainly possible.