Nowadays i am very confused about that usdt, it become terrible about more than blockchain, i stopped to use it.
If you want to buy btc, you can do it with usd or tether, but I dont understand for what reason people buying usdt and hold it.
Holding USDT is having the same risk as holding your cryptocurrency in an exchange wallet. In case of the second option, your coins are being held by the exchanges and they can get hacked, or the owners may vanish with your coins at anytime. On the other hand, if you hold USDT then you are holding the tokens by yourself. But these tokens can become worthless, as their real value is being held by the individuals who store the backup for Tether tokens.
Keeping your funds on exchanges is not the right idea, its better to use purses specially made for each cryptocurrency.