Even if the Optimism team had noticed and temporarily suspended bridging transactions via the sequencer in a theoretical attack, an attacker could still have wreaked havoc on layer 2 decentralized finance (DeFi). By using fake OETH, any attacker could drain decentralized exchanges and exploit lending platforms with unnecessary collateral. The exploit would have likely caused irreparable damage within the Ethereum ecosystem and Layer 2 users could have seen all their funds go unused, with no assets at the other end of the bridge. Together, Optimism, Boba, and Metis had roughly $750 million locked up in DeFi on the day the vulnerability was reported, nearly all of which was at risk.