And all of that ignores the fact that ETH could be attacked in a similar way. POS is not a flawless security model and in order to attack it, the attackers would not have to buy a shitload of ASICs and the network is only 1/4th of the value.
Here I will refer you back to my answer to @DaveF (sorry for the initial mistake):
Just as another thought experiment would be how much would it cost to get enough ETH while people are selling theirs to do this to launch your own 51% attack on ETH.
The fact that there is no real work involved just having enough money to buy enough of a specific coin has always been a weakness of all POS coins.
And now that there are ETH ETFs there is an incentive for people to be able to short the ETFs if they think their value will go down.
Think about it, get enough funds to buy the companies I discussed above that host a bunch of the ETH staking nodes, while simultaneously buying ETH and spinning up your own nodes and then a simple 51% attack against ETH.
-Dave
In theory, a 51% attack on Ethereum would cost > $300B × 50% = $150B. (Bitcoin and Ethereum have apparently just dropped 11% and 21%, respectively, in this past 24 hours.)
And a 34% attack would cost > $300B × 33.3% = $100B.
The stakers would lose that money (in a Rival Goldfinger attack), and they would only be able to gain $300B, and
only when assuming that the Bitcoin investors share the costs equally. If not, it would thus take at least 33.3% of the Bitcoin investors to participate in an attack in order to break even in terms of costs and gains. (And for a 51% attack, it would require at least 50%.)
Now,
if the Bitcoin investors is somehow able to keep their attack a secret, they would in theory not need to beat 33.3%, but only ~0.01% (in the current moment), which is the actual fraction of staked Ether compared to what's in circulation. But on top of the need to keep it a secret, this theory also assumes that safe guards like described in
https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/#finality isn't implemented or doesn't work.
(Edit: Sorry, my mistake! I mistook 33M ETH for 33M USD when I looked up the amount. The amount of staked Ether is currently 28%, not 0.01%. x))
Last but not least, in order for the steal to be finalized for good, the attackers would also need to confuse the Ethereum community of whether the reorg was malicious or not, assuming that the remaining 66.6% of the Ethereum stakeholders would otherwise just revert the attack afterwards. (Edit: Think of what happened with the Ethereum Classic fork.)
For a 51% attack, the attackers would be able to force a hard fork when the "honest" stakeholders revert the attack. But unless again the attackers can succeed in confusing the whole community, the community and investors will know which of the two chains they ought to support, if they don't want to support the chain that actively tries to undermine its own currency.
[...] If it becomes publicly known that an attack is planned, there is a chance that BTC whales will pool funds and fight back. They could approach ASICs manufacturers, miners, and they could say "if" the attack is pulled off, we will pool 10 billion dollars to defend against it in some creative way. There are many ways to raise the price for the ETH attackers and keep in mind that the ETH attackers need to liquidate in the first place.
Okay, here we are talking about potential mitigation strategies. I also think that Bitcoin investors must be able to do
something. The question is just what? (I'm personally still thinking that planning a switch to PoS themselves might seem like the best option, btw.)
While I agree that one might be able to do
something with $10 billion, I'm not sure that trying to pay the "honest" miners more would be a very good strategy at all. My concern is that this would just immediately incentivize all miners to try to make it seem like an attack is underway, in order to cash in on this mitigation money as a large bonus to their normal earnings.
I guess the Bitcoin investors could try to buy mining farms directly, instead of simply raising the on-chain rewards. But that would then still incentivize such mining farms to help fund the attack (which I explain in my preprint paper can seemingly be done anonymously via smart contracts).
Last but not least, one also has to ask the question of whether the Bitcoin investors are really that cohesive when all any single investor has to do to avoid the threat, and avoid paying their share of the 'mitigation money,' is to just preemptively trade their BTC for ETH (or perhaps another PoS coin). With the shear amount of BTC that is traded each day on the blockchain, even the large players (at least most of them) should be able to make this move pretty quickly.
But what do I know about the fortitude and cohesion of the Bitcoin investors as a group: not much. This is only speculation on my part. What do you think in this regard?