How Does the Cost of a 51% Attack on PoA Compare to a Pure PoW Network?

A 51% attack on PoA is significantly more costly than on a pure PoW network, especially one with a low hash rate. The attacker must acquire 51% of the total hash power and 51% of the total staked currency.

In pure PoW, only the hash power is needed. This dual requirement means the attack cost is the sum of the PoW cost (hardware/electricity) and the PoS cost (acquiring/staking tokens).