The numbers Tether produces don't really make sense. They're widely assumed to be massively fraudulent - although we can't prove this without being able to audit them. And of course their keep pushing back on attempts to do so [1], which pretty much confirms the assumption.

[1] https://blockworks.co/news/tether-pushes-back-timeline-on-au...

Yeah but I can also make a webpage saying I have $10 billion dollars, doesn't mean its a true statement. If it was at least a 3rd party that was auditing it, I would put more stake in it.