How Does Proof-of-Stake Inherently Defend against a Sybil Attack?

Proof-of-Stake (PoS) defends against a Sybil attack by tying a validator's influence directly to the amount of cryptocurrency they have staked. To gain a majority influence and launch an attack, an entity would need to acquire over 51 percent of the total staked supply.

The financial cost of acquiring this capital makes a Sybil attack prohibitively expensive, as the attacker cannot simply create numerous free, fake identities to overwhelm the network.