Have you looked into the mechanics of this trade? The crypto loans I'm aware of are all significantly overcollateralized. You would have to pledge say 1m BTC to get 0.8m BTC worth of USDT which you could then sell for dollars. If you succeeded USDT tanks, everyone who holds USDT would be rushing for the exit, wiping out the crypto you pledged as collateral also. So you succeed in losing 20% of your money on the initial USDT trade and almost all of the value of the crypto assets you pledged for the loan as well.
These markets are nowhere near as flexible and liquid as regular fx - I would be amazed if you ended up making money overall on this kind of strategy and the execution risk is significant.