> The likely fraudulent business model would be printing USDT that aren't backed by USD, purchasing cryptocurrencies with it, and then pumping up the value of that cryptocurrency to realize gains.

If Tether prints, say, $100M USDT, and buys Bitcoin with it, they'll move the market up. But then when they cash out their gains, they'll move the market down.

It's still a profitable business model, because they can get ~100M (minus market impact costs) for basically nothing, but the money isn't from manipulating the market, it's from printing $100M USDT from nothing.