@ArticMine: This kind of attack would be possible only in an "intermediate" stage of the coin evolution: when there is enough volume/liquidity to borrow that many coins from newbies, but the community is not mature enough that most of coins are hold by people who never would trust a "pirateat40-like" system.
Pirateat40 did it when Bitcoin was smaller than many of today’s POS coins. I do agree that one does need a certain amount of maturity in the coin for a significant debt market to develop. It is for this reason that we have not yet seen this kind of attack on POS coins. At the other end of the spectrum we see the failings of the fiat currency system in particular the collapse of 2008. This again was driven by the same issue: Stake with little or negative exposure. So if instead of pirateat40 one can consider the Conrad Black attack. https://en.wikipedia.org/wiki/Conrad_Black Pirateat40 and Conrad Black have one thing in common: Legal problems with the United States government.