Does anyone know what the most profitable illegal businesses are in order?

The casino is the most profitable, I believe. I also think one moonshine still can supply a few speakeasies. So, getting that scheme set up is a pretty good way to make some dough.

The small time stuff like card and dice games probably bring in the least, but I don't know that for sure.

You also have to figure in the market. If you saturate the area with prize fighting rings, for instance, they won't all perform to their potential.