Ethereum architect Justin Drake believes that a 51% attack on Bitcoin would be more economically feasible than on Ethereum. He estimated it would cost around $10 billion, significantly cheaper than the costs required for similar attacks on Ethereum. This assertion stems from his experience leading the work on Ethereum’s proof-of-stake (PoS) implementation and his involvement in the Merge, which transitioned Ethereum to a PoS model. His views were echoed by Grant Hummer, co-founder of Etherealize, who believes Bitcoin’s security budget makes it vulnerable to such attacks. 51% attacks occur when a single entity or group controls over 50% of a blockchain’s network’s power, giving them control over the network. Hummer estimated the cost of successful attacks on both cryptocurrencies but highlighted how easy an attack would be on Bitcoin, while Ethereum presents more challenges. Drake further argued that even though it’d be difficult and costly to achieve complete control over Ethereum (requiring 50% + 1 stake), a wealthy nation-state could theoretically pull it off. He explained this cost is significant but still attainable, considering the current market cap of Ether at nearly $89 billion. This figure underscores the substantial investment required for such an attack, which would likely lead to further price appreciation in ETH. Lightblocks’ CEO Matan Sitbon highlights Ethereum’s inherent advantage as its social layer allows community intervention and can identify attackers, offering a unique defense mechanism absent from Bitcoin’s proof-of-work (PoW) system. Another point of discussion is that if Bitcoin experiences 51% attacks, the community might resolve them with a new fork. This would result in the delisting of old tokens and leaving the compromised chain irrelevant, according to Pavel Yashin from P2P.org. Lastly, Ordeez CEO Hassan Khan believes that while theoretically possible, practical challenges for Bitcoin’s 51% attack are high. He emphasizes the significant computing power and energy required for such an endeavor, making it unlikely in practice. Conversely, he highlights Ethereum’s PoS system introduces economic and governance mechanisms that make a successful attack highly improbable.