The problem is that our law enforcement agencies do not prioritize fraud. The investigations can be time consuming and the targets are usually pretty wily, so the best case scenario is you get an AG who'll do a civil case and try to negotiate a partial disgorgement (this is what happened with the "Trump University" case, for example).
The problem with this is that it leaves the fraudster standing, and the lesson he learns is Crime Pays. You do this for a few decades and it really starts to erode people's faith in society.
And so here we are.