binance and the others aren't net USDT creditors. it doesn't matter to them (financially) if USDT is unbacked and loses all its value. in that situation, binance is still solvent since it still controls all its depositors USDT.
in that situation, it's the holders of USDT on binance that lose money, not binance. this is why kraken always had a USDT/USD market. they can't risk redeeming USDT for real USD because that would expose them to bitfinex counterparty risk.
Binance is one of the main Holders of tether according to tether rich list. As they negotiate high volumes of tether, it's highly unlikely that none of that there is theirs. It's the same as saying they have no btc.
I think thats not even possible because they receive fees for each tether that is negotiated there.
the vast, vast majority of rich list holdings are
customer deposits. just like the vast majority of BTC held by binance are
customer deposits. if USDT loses all its value, that doesn't make binance insolvent. just like if BTC loses all its value, it doesn't make binance insolvent. in those cases,
binance's customers are the ones who lose all their money because their holdings are devalued. binance can still fulfill all USDT and BTC withdrawal requests. your claim that tether's inability to pay its creditors means insolvency for other exchanges makes zero sense.
sure, binance takes fees in USDT---i'm sure they hold some amount of USDT as assets, and i'm sure it's liquidated
very regularly. CZ is not a moron. they will only hold USDT (exposing themselves to bitfinex as a counterparty) for as little time as possible. if binance wants to hold USD, they open bank accounts lol. plus, if you're just talking about USDT trading fees, you're talking about their profits---losing some portion of their profits doesn't equate to insolvency.