Those would have to be some amazing bribes. A full 10% of the ETH supply is locked up in the staking network, and neither the original capital nor earnings can be withdrawn until about six months after mining is eliminated. The dev teams themselves were granted significant amounts of staked ETH by the Ethereum Foundation.

The production staking network was launched in December 2020, was upgraded in mid-2021, and since then there's been extensive public testing of the merge with the rest of the network.