The problem of most Proof Of Stake networks is the ledger will be open to attacks if there's isn't any check-points implemented. But if there are check-points being done, then the network is reduced to a "consensus" through "ask a friend", and not from the staking of the tokens itself.
I agree with this statement.
I don't really believe that any attackers would be able to actually confuse the Ethereum community/traders of which is the honest and the malicious chain in practice, however. Do you agree with this?
In theory, there are some attacks in POS chains that would make the malicious chain indistinguishable from the honest chain, therefore they need check-points. But the problem - how do you decentralize check-pointing. And for those projects that claim they have, they are hard to analyze.
But it's still a valid point, and why some might choose PoW over PoS. However, if PoW truly has this vulnerability that a rival blockchain could profit from a 51% attack, then its not certain that PoW will remain the more favored protocol, and Bitcoin might want to consider a switch as well.
To find out is simple - Attack Bitcoin. If the attackers are successful with that, then Bitcoin has no right to exist.