Watch the sell orders rack up in real time: https://ftx.com/trade/USDT/USD
Note that while it's a good proxy this isn't same as going to the issuer ( https://tether.to ) and getting 1USD in exchange for 1USDT. Tether is still honouring 1-1 conversion for a minimum of $100K.
Also, they reserve the right to delay fulfilling your order indefinitely, so they don't actually guarantee anything even if you did buy directly from them.