Catching the Ponzi - The small ones get caught, the BIG ONE endorsed

They catch the small fry, whilst the grandest Ponzi of them all goes on unabated, sucking in enormous assets and civil rights to it's ever quickly spinning black hole.  How is that for a graphic image?

How can this stuff go on for decades?  Aren't there tax and SEC filings, including prospectus that should allow a 5 minute check to stop the Ponzi before a decade passes.   Why is this so hard to detect, it should be something a 12 year old could be taught to do?