51% attack

[squatter]

You mean the Chinese government? The majority hashrate is already located in China:
https://www.coindesk.com/highest-in-2-years-65-of-bitcoin-hash-power-is-in-china-report-finds

We're still talking about private companies running these mining operations, not the government. The confiscation of private mining facilities to launch a 51% attack seems rather unlikely as China knows better than to kill their own cash cows.

Well depends what their intentions are, they might confiscate all the farms to launch the attack and destroy btc to be able to force on public their own "cryptocurrency".

Then they might cripple the ASIC manufacturing industry, which China overwhelmingly dominates. China is trying to boost its exports, not restrict them.

In this way, they would have the best of both worlds, the biggest competitor would be gone, and everyone in china would have no other choice but to use their centralized government shitcoin. It's actually scary what countries as powerful as china can do to bitcoin.

It wouldn't be gone. A 51% attack only allows attackers to perform double spend attacks and censorship. The costs are absurd and users can simply wait out the attack. Worst comes to worst, the network can hard fork to brick SHA-256 miners and introduce a new POW algorithm.

With the DCEP project, I don't think they are necessarily trying to dethrone Bitcoin. Rather, they are putting their fiat currency under tighter controls and surveillance.

[seoincorporation]

...
You misunderstand what a 51% attack can achieve.

A successful 51% attacker would mine and build a secondary blockchain in secret, with whatever transactions they like included in it. Once their own secret blockchain is longer than the main chain, they broadcast it to the network. Since they now have a longer chain with more proof of work, the rest of the network would automatically switch to this secondary chain, and the previous main chain would be abandoned. Any transactions which were included in the previous main chain but not in the newly accepted secondary chain would be reversed. This can happen after theoretically any number of confirmations, although with each confirmation it becomes exponentially harder and more expensive. However, a successful 51% attack would, at a minimum, be able to reverse or double spend transactions with 1 confirmation.

Most exchanges wait for at least 3 confirmations before confirming bitcoin, and some still wait for 6.

Thanks for the explanation o_e_l_e_o, after reading your comment i read more from other sources about the topic. You are right, it is not about a double-spend problem, it is a full block replace and a chain replacement.