For clarity, there's a variety of very suspicious things about Tether. While they're clearly receiving some USD, they're printing $100M in Tether every couple days now.

If I claim to have $50k, you'll probably assume it comes from my job. If I claim to have $2B, as Tether does, you'll probably want some proof. Tether's promised regular audits, but they've released none and their supposed auditor has now scrubbed any mention of them off their site.

There's been a fair amount of conspiracy-theory-like thinking around Tether in general, with people making a morass of self-contradictory claims about it and shifting their positions every time someone points out one of the claims doesn't stand up.

To be fair, tether really is quite shady. I think the real truth is probably somewhere in between.