There is an assumption behind your question to the effect of saying "If we assume Tether is not, ultimately, a fraud, it seems like the only way..."
That is, IMHO, a questionable assumption.
Now, "fraud" in this case too strong a term. The intent to defraud may not be explicit in Tether's internal conversations and practices.
All business ventures by definition involve risk, and corporate structures and venues and liability shields and so forth exist precisely to create a space for risky ventures to be undertaken without failure leading to death or personal poverty for the principals. In those cases, the customers, investors, and other participants are also partaking in the risk, based on information that is deliberately- sometimes responsibly, sometimes incidentally, and sometimes maliciously- incomplete.
At the end of the day, when the full accounting is known, a post facto judgement of fraud vs speculation may be rendered.
But the assumption that Tether is behaving as one might want one's bank to be behaving, in terms of customer/user risk exposure, should be strongly, strongly questioned.