And the alleged fraud is that they're creating USDT out of thin air, and spending them to buy BTC, in order to manipulate the price of Bitcoin upward. If you're a Bitcoin bull, then that's almost a selling point. I don't think any of this ends well, but I see the short-term appeal.

People don't appreciate how slowly government works, especially on financial crimes. Liberty Reserve was blatantly illegal and technically simple, without even the blockchain fig leaf. It operated openly for seven years. Then the government arrested the founder, and sentenced him to twenty years in prison.