While the PoW monopolizes on heavy computation-based problem solving to gain reward, PoS relies upon the staked tokens. If the staking node publishes an illegal transaction, then the staked value is lost by the node, and it can be banned in the future to participate in consensus.
This makes PoS more affordable as you don’t require expensive mining rigs to compete to participate in the network. It also leads to less electricity consumption. With some sources claiming it to cut down electricity consumption by 99% (confirmed by Ethereum team), making it the green alternative for cryptocurrencies.
In order to make a network sustainable, the teams must ensure that the transaction validation process is energy-efficient and makes it impossible for any single entity to become the majority player. The PoW-based networks incentivize miners for upgrading their equipment timely, which again isn’t very economical. In line with this, the crypto and blockchain community believes that Proof-of-Stake (PoS) is a better choice when it comes to choosing a secure and green consensus mechanism.