Let me clarify, adding some additional events that I think will occur:
1. China picks a date and declares it will utilize huge amounts of hashrates for mining Bitcoin for 24 hours (at the cost of ~ 20 Million dollars, per hd49728's reply, which is pocket money for countries), implementing a 51% attack.
2. Scared individuals and institutions sell their coins ASAP, generating a colossal "run to the bank". The BTC to USD rate tanks.
3. The decline in BTC, along with the threats of a player of endless resources, make the mining farms stop mining Bitcoin. They divert their resources to other cryptocurrencies. Consequently, on the attack date, the total computational power of Bitcoin miners is significantly low.
4. Intended to rent huge amounts of hashrates, China finds itself with almost empty mining pools. The attack turns to be significantly cheaper than intended in the first place.
What do you think?
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(a) Nah, I don't think it will bring any incentives for them, on the contrary, it will cost them millions if not billions, doesn't make sense at all. 51% attack has never been attempted because it's a futile effort to stop bitcoin.
(b) Not feasible, and it is a worst idea to begin with.
(c) Not that I can think off, again, it's because of the huge money involved. And no country and individual are willing to do this because they simply have nothing to gain.
(a+c) Well, it should be compared with the cost of the alternative. If China wants to ban Bitcoin, it must be because it has something to lose (for instance, losing the ability to spy on its citizens). In such a case, China has everything to gain by taking it down.
1. Cost is too expensive. It is cost to have enough hashrate that is more than 51% and keep it in a few hour.
The cost does not only about equipment cost. You don't need to own equipment to run attack. What you need is hashrate.
The Estimated cost of 1 hour 51% attack on BTC network is $716,072. It is not absolute correct estimated cost but you can refer to in
https://www.crypto51.app/coins/BTC.html2. The network, nodes will detect the attack and they will react very fastly.
3. Cost is expensive but chance for success is very low. It is not deserving any attack attempt.
In a sense, 700KUSD per hour is not a lot. Furthermore, Chinese miners account for 75% of the world's Bitcoin hash rate(
https://fortune.com/2021/05/24/bitcoin-china-crypto-miners-crackdown/); shutting (some of) them down will result in a huge discount over this price. But even at that rate - a 24 hour attack will cost ~17 Million USD, which is pocket money for governments.
Why do you think the chances of such an attack being low (assuming that China *wants* to implement it)?
It would be possible for a country to build up to 50+% of mining power but it would probably be futile.
There's a good chance a snapshot will be taken and the coin will be reincarnated and functioning with a different algorithm. If this doesn't occur, there's potential some governments use a snapshot to reimburse investors or offer some sort of compensation (especially if large companies or even the government have a stake) - either that or another set of countries would launch a counter-attack on the 51% attack being done by the attackers.
Do you agree such an attack will result in BTC price tanking? in such a case, the rewards granted for newly created blocks will tank, removing a huge proportion of miners from Bitcoin, undermining the faith in Bitcoin. Then, to get those 50+% will be easier, won't it?
How is it possible to recover a snapshot? Shouldn't all nodes agree to it in a decentralized manner? How plausible is that in your opinion?
