First of all you have to delegate the custody of your funds to get a fiat loan. You are giving away generation al wealth and power to someone else for a quick buck. Lets say you are responsible and not greedy at all. But you are introducing counterparty risk, like with celisuis, blockfi, there’s always risk. Many people will get overconfident that the price of bitcoin will never go 80/70% down so they will get greedy and that can accelerate the downfall of the price because of forced liquidations. Banks will love this because this is the game they created and they control : they get your collateral for free. They did this in 1929-1933 they did it again in 1987, again in 2008 and also in 2020. There’s no logical explanation to say that this will not happen with bitcoin. Is the fiat game. Is to give them power in exchange for what? A quick buck of fiat poison? Not worth it for me. But hey! Everyone is free to do whatever they want!