According to the second most popular cryptocurrency co-founder Vitalik Buterin, after the proof of stake consensus algorithm implementation in the Ethereum blockchain, it will become safer and more expensive to attack than Bitcoin.
Vitalik Buterin particularly mentioned that after turning to PoS, possible attacks will become high-priced and it can make Ethereum network more secure.
With PoS integration in the Ethereum blockchain, users will lock their ETH in smart contracts and will be enable to approve new blocks, in lieu of spending lots of computing power and electricity like they do in PoW systems. If users who lock their cryptocurrencies misbehave, the cryptocurrencies they locked will be cut.
More Ether staked means there is a higher probability that the block will be confirmed. In this system, after the new block is created there exists a certain period in which the block can be challenged and be possibly confirmed to include illegal data. In such a case, the dishonest validator’s stake is cut and the challenger earns the stakes lost by the validator.
Thus, to make an efficient attack on this system, one will have first to place a huge amount of crypto to be able to create numerous blocks that could be lost if the blocks are proven to be illegitimate.
This means that under PoS consensus, validators will have skin in the game even after creating a block and can lose the blocks if they are recognized to be illegitimate.
Consequently, the potential attacks will become awkward and overpriced, and this is supposed to be an improvement over PoW, based on the opinion of Vitalik Buterin.