Often, when a cryptocurrency tanks, holders of a rival coin will tease them with "SFYL" - sorry for your loss.
But the entire industry needs to keep an eye on Tether's USDT token, because if something were to happen to it, the result could be everyone's loss.
That's because the coin, also known as tether, has become a pivotal source of liquidity for the crypto markets. Without wanting to further spread fear, uncertainty and doubt (FUD) in a community that's had more than its share, a collapse of tether would be extremely bad for these markets, causing a ripple effect and, in the worst case, conceivably toppling exchanges.
https://www.coindesk.com/big-fail-tether-might-still-cryptos-ticking-time-bomb/