You have proven nothing. There is no market for formerly large stakeholding keys. But you claim by declaration that they are easy to get and at significantly below market price. And that the current mainchain will just magically switch to the attackers chain.
Making a wrong statement is not quite the usual standard that comes with the word "proof"
I have submitted a problem statement, which, if satisfied would enable this attack. If you disagree with the statement, let's hear your rebuttal?
I claim it would be 'easy' to acquire a historical key because it would contain no funds, and thus be worthless to the seller. That seems fairly well justified rational behaviour to me.
I thought in crypto economically unviable attacks are not relevant.
Did that change? I must have missed the memo.
Since you dont have any calculations about the cost of actually acquiring the recent keys, nor even a definition of what recent is, nor how even if you magically got those recent keys how you get the big active accounts to switch chains, it does not pass the common sense test.
But if you change it to reflect that you need to fool existing large stakeholders to transfer all their funds to a new account, sell them the newly emptied key. Do this half a dozen to a dozen times. All within a few days. Then create a fake chain and then make the largest accounts, like the central exchanges with lots at stake and long time accounts to all switch to the fake chain, ok, you got me. with those sets of facts, yes you can compromise a chain.
However, an equally ridiculous set of assumptions can be used to take over a PoW chain. So this is not anything specific to PoS, it is social engineering attack mixed in with mass hypnosis. Why not simply the attack where you ask everyone to just send you all their funds? That would work too
James