According to Vitalik Buterin, it is easier to penalize participants in a 51% attack on a Proof of Stake (PoS) network compared to a Proof of Work (PoW) network. In PoS, the attackers can be punished directly, while in PoW, the only option is to change the algorithm, which negatively impacts all users. Additionally, once the algorithm is changed, the network remains vulnerable until the ASIC ecosystem is re-established.