Many cryptocurrencies have been destroyed by 51% attacks. Under the hood, those currencies and bitcoin are virtually identical. The only difference is that bitcoin has a lot more riding on it and a lot more people who care. And that's really the only thing that could save it. It may be overblown to say this is the end of bitcoin, but it certainly is the end of the status quo. Something will have to change, either in the bitcoin protocol or community, if bitcoin wishes to remain afloat.
Many cryptocurrencies have been destroyed by 51% attacks.
Would you have a link to a writeup of these handy? I'd like to read up on this.
(a request for info, not doubting it in the slightest)
And apparently the sky is falling. From Ittay Eyal and Emin Gün Sirer at Hacking, Distributed:
But the fact is, this is a monumental event. The Bitcoin narrative, based on decentralization and distributed trust, is no more. True, the Bitcoin economy is about as healthy as it was yesterday, and the Bitcoin price will likely remain afloat for quite a while. But the Bitcoin economy and price are trailing indicators. The core pillar of the Bitcoin value equation has collapsed.
They note previous bad behaviour from GHash (which GHash attributed to a rogue employee).
Their proposal is a hard fork, with different parameters (to make huge mining pools no longer an economically rational choice), but respecting the blockchain to date so they can reasonably keep calling it "Bitcoin".