There are many powerful entities which can hide the truth and we only know part of the truth or just what those entities want to leak to the public including us. Sometimes they don't intentionally leak information but there are loop holes in their systems which fail to cover their traces. Generally, we never know the whole truth from governments or big companies like Tether.

No one imagined Enron can collapse even with an audits from a big audit company. No one imagined FTX can collapse within a week. There are some people who are very experienced actually smelt about risk from those companies before they collapsed and filed for Chapter 11 bankruptcy. Unfortunately, most of the crowd who invested money to those companies did not know anything about risk.