As the Ethereum Merge draws near, a key factor that will determine its success is the relative security of the blockchain under a proof-of-stake (PoS) regime. Experts say that Ethereum’s PoS chain will maintain the network’s security but at much lower cost. In a proof-of-work (PoW) system, counterfeiting cryptocurrencies requires a singular miner to control more than 50% of the entire network. Even then, mining requires a significant amount of electricity and hardware, making it incredibly time consuming and costly to take control of the network. Other network nodes can detect such an attack and potentially fork away from the nefarious miners — a layer of social consensus that makes a matured PoW system such as Bitcoin nearly impossible to attack. Similarly, in PoS systems, validators — who are the equivalent to miners in PoW — are randomly assigned to produce blocks proportional to the number of tokens they hold as they verify transactions on the blockchain.
Full story : What To Expect From Ethereum Security and Privacy After the Merge.