Who would be buying the tether? Every trade on an exchange has two sides, who is going to buy USDT that isn’t worth anything?

For example, the $449 strike SPY call expiring in 27 minutes has a bid of 0.00 and an ask of 0.02, meaning nobody will buy if you try to sell the call, but a market maker will sell you one for 0.02. If tether was worthless, the same situation would happen, people would be willing to buy for 0.00 and sell for a bit more than 0.00