2/3rds is required for a full 51%-style attack in PoS.

https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQs#wh...

There's a lot of misinformation regarding PoS. Vlad Zamfir has spoken a lot on cartel attacks and how they're mitigated, but the biggest, and I mean bigger than biggest, argument against all of these attacks is that it's always detectable by honest nodes shy of 2/3rds attack and it defaces the value of the coin itself to attack at that volume.

You can always buy them out. But honestly, a 51% attack seems like a much less likely way for ethereum to fail compared to it just not living up to the hype.

A buyer requires a seller. Who's to say they would?

Buisness plan: Get a 51% stake in Ether, and hold big users hostage?

That works until the big users hard fork and take away your ether on their fork. It's pretty much a failsafe that always works at the cost of possibly destroying all trust in the network.

Giving everyone a nuclear button is an interesting solution.

> Also once a majority of stakeholder hit 51% there is no way to take away the 51%

You could do a hard-fork and slash their stake. In PoW, you can't do this.

> With PoW, an entity could theoretically out mine the 51% attacker

Not in the case of "selfish mining attack", where you may never know that an attack is happening until it's too late, you'll have little chance in defending with hashpower since the attackers will have a significant head start...

> You could do a hard-fork and slash their stake. In PoW, you can't do this.

So ... theft?

Theft of what exactly? Each fork is as valid as any other fork, the challenge is in agreement.

You should really be careful with how you play with definitions, as that will lead down to a slippery slope. Remember that time when someone managed to generate 184 billion bitcoin? With your reasoning, we can now say that the succeeding hard-fork to 'fix' the issue by slashing the bitcoins was theft.

> Remember that time when someone managed to generate 184 billion bitcoin?

you're being intellectually dishonest or even outright manipulative here.

there were never 184 billion coins created on bitcoin chain, there was a bug in validation logic of bitcoin client that made it follow the chain that was invalid.

are you seriously trying to compare that to stealing coins from somebody on a valid chain?

really?

> are you seriously trying to compare that to stealing coins from somebody on a valid chain?

They're not stealing coins from someone on a valid chain, they are forking away to another chain and slashing the user's stake. The user will still have all their coins on "their" chain and it's up to everyone else to decide which chain is "the right one". If the 51% user is truly malicious, the majority of network participants will move away to the new chain, rendering the 51% user's tokens (near) worthless.

> If the 51% user is truly malicious, the majority of network participants will move away to the new chain, rendering the 51% user's tokens (near) worthless.

so being successful is punished by destroying all wealth of the richest participant in the network? nice.

No, being malicious is.

having lots of money is malicious?

No, it's not, that's why I said

> If the 51% user is truly malicious

Having 51% doesn't automatically make you a malicious user. People also wouldn't move away to another chain simply because someone or some group owns 51%. They would move if said person or group abuses the power they get from owning a majority.

Now you've really tangled yourself in a big web.