[amluto]

> For a 51% style attack on a PoS chain, you need to acquire a majority of staked coins.

Not really. All you need is a controlling vote for enough confirmations. At 51%, you’re very likely to have a controlling vote. Below 50%, it’s still possible.

[hndamien]

And that is why these are not decentralised solutions. Just maintain a controlling stake and you are good to go!