Even if the Optimism team had noticed and temporarily paused bridge transactions via the sequencer during a theoretical attack, an attacker could have still wreaked havoc on layer 2 decentralized finance (DeFi). Using the falsely minted OETH, any attacker would be able to drain decentralized exchanges and exploit lending platforms with useless collateral. The exploit would have likely caused irreparable damage within the Ethereum ecosystem and layer 2 users could have had all of their funds rendered useless, with no assets left on the other end of the bridge. Combined, Optimism, Boba and Metis had around $750 million locked in DeFi the day the vulnerability was reported, almost all of which was at risk.