Can you (as a node) manually choose what block to bet on in Casper?

Question

Ethereum plans to move to the Casper proof of stake algorithm in a future version of the network. However, as nodes are betting on which block will be produced next, does that mean (as a node) you can manually choose to bet on which block is produced next.

If true, someone with large amounts of ether could theoretically choose a block which hasn't been bet on, and bet more than what is betted on the block the majority consensus is betting on. This way, the person with large amounts of ether could manipulate the network to work for him/her self.

Answer 1

Yes and no.

There's no way to enforce any given betting strategy in either PoS or PoW. For example, in PoW, there's no way to force miners to never mine on an attacker's chain. So, yes, a validator could be programmed to bet in any possible way.

Betting doesn't quite work this way, however. There's been multiple versions of how betting works, what exactly is bet on, and in what order. However, what I've always seen is that validators give a percentage bet. For example, the equivalent of "I believe that this block has at least a 60% chance of being true." Hopefully, every block will be bet on, in one way or another, by every validator. A "forgotten" block will probably be bet against by the majority of validators.

But what if the majority is with the attacker? This is essentially the 51% attack applied to PoS. The social counterattack, in PoS world, is to fork the chain with a new rule that deletes all the attacker's stake. Such an attack would certainly damage faith in Ethereum, but it probably wouldn't destroy it.