I wondered about this too. Vitalik is real, so I'd be curious to read a deeper analysis. With sybil attacks its important to realize there is no upper bound on

I wondered about this too. Vitalik is real, so I'd be curious to read a deeper analysis. With sybil attacks its important to realize there is no upper bound on effort or sophistication. A sybil can use botnets, social engineering, machine learning, etc.