I think that your missing what I have been told is the reality. I suspect that you are correct that PADI principals, per se, doesn't make as much as many expect, but I have been told that the "off the PADI books" profits from items such as insurance "finders fees" (nice name for kickback, bribe, lamordida, el chanchullo, etc.) that are paid to individuals by the insurance agents who place the actual coverage. This is, as I understand it, a practice that is common to all of the private, for profit, major agencies.