You raise a really interesting question there. I always ignore Tether as a joke because it’s just a crock of shit. But what happens if someone makes a run on Tether? They publish accountability reporting which, crucially, tells consumers to inform themselves of the general risks and potential legal issues. It would appear that Tether does have ~80bil in USD assets of various maturity. Only ~400mil of that is cash. There’s another ~20bil in other assets. If there is a run on Tether, it collapses at under 1% of its balance, ie of the ~100bil in Tether only ~400mil/0.4bil of it could be converted to USD today (well, 2023-12-31 per the last report). Since it’s not insured, there’s nothing to prevent a run on it. Its value is supposed to be its ability to be converted to USD, so if a run occurs and people are not able to make the conversion, its value plummets and can only be rescued by the fire sale of assets well below market value. Tether, more so than fiat currency, has completely made up value.

I’m not a finance person so I bet someone that knows more than me has already done a better job of explaining how Tether is a scam.