I think this is due to the spread of this alarming virus. all crypto users choose to sell all volatile crypto assets such as bitcoin and ETH, then they buy stable assets like this USDT. when the market still looks bad investing in stable coins may be the best way to reduce the amount of loss in assets and coupled with the many POS programs that have begun to run. I do not know whether the program is POS or just a Ponzi scheme, but I see many people who follow the program. and I am sure when all things improve and the world economy has returned they will return to invest in fluctuating crypto again. and prices will soon improve.