that is true, but the whole ethos of DeFi is to make the process of mining as decentralised as possible. Have many validators, separated across the globe etc. O

that is true, but the whole ethos of DeFi is to make the process of mining as decentralised as possible. Have many validators, separated across the globe etc. Obviously, there are still chances that all the miners conspire and kill the system, but the chances of that are decreased with increased decentralisation in the mining and validation process.