The Nxt community was debating "rewriting history" to rollback the theft from Bter! The users become the attackers, and in their echo chamber they decide to make up whatever truth appears convenient at the time. If you don't see this, then you don't want to see it.
On the topic of a single malicious cabal attacking the network, the cabal needs only 51% of what is currently staked, which may be significantly less than 51% of the money supply. Furthermore, the cabal can attack with coins they once had but have since sold. This is the nothing-at-stake problem (aka the history-rewrite problem). This can be prevented with checkpoints or if the developers sign blocks as valid, but then your decentralized currency is no longer decentralized! We saw this with the viacoin roll back or fork it and get rid of it.
Lastly, the idea that some special sauce known as "transparent forging" will require 90% of the critical resource to attack is a highly dubious claim. I strongly suspect that the following PoX Theorem holds:
A malicious user controlling 51% of the critical resource X in a PoX distributed consensus system can attack the network.
Bitcoin was "rolled back" at one
point in the early days. Whether objective or subjective, no one wanted 92 billion bitcoins to remain in the blockchain and controlled by a single entity. If that were to happen today I almost guarantee the miners would find a way to roll it back.
The fact is nxt worked as advertised. The developers released a patch to roll back the transaction but it was unsuccessful, proving that they did not have complete control over the network and the integrity of the currency remained intact. POS is subject to similar game theory type stuff as POW. Why would someone who has a large stake in the system attempt to compromise it?
We can debate whether POW or POS can be compromised, but the fact is cryptocurrency is proven to be sound money once relatively mature. If 5% (or 7% in bitcoin's case - mtgox) of US dollars had somehow been stolen, you can be guaranteed that the federal reserve would have arbitrarily started a counterfeit program (2008 bailouts and QE). Our systems are better and the beauty is users have a choice of POW or POS.
i see plenty of differences:
Bitcoin's "rollbacks" in the past were from code
bugs, one of which was exploited to generate a massive output of invalid BTC's and the other which caused a fork. an immediate
consensus was gained from the community to patch the technical bugs with new code prior to it being released; otherwise repeated occurrences of the problems could reasonably be expected which threatened the long term viability of the system itself.
in NXT's case, the NXT stolen was due to a weakness in Bter's security, not a bug in the NXT code, let alone one that threatened the viability of NXT. for crony economic reasons only, a rollback was offered in the form of a patch from the devs despite what looked like a consensus
not to offer it. this makes it much different from what happened in Bitcoin and was an expression of the biased motives of the stakeholders in charge of the code and that of the influence of Bter. the next time something like this happens, no one can predict how they will act, whereas with Bitcoin, you can be sure no one will rollback code just to save someone some money but only to save the system.
OMG LOLZ... hahaha
