I'm not saying that he isn't evil enough to it, I'm saying he isn't stupid enough. I just can't imagine the money being worth it. The gloryholes are mostly being used by students, they can't make that much. If he even gets a cut, how much could that be after subtracting the money the girls and Quinn get? One trip to McDonald's a week?
And even the rich old men: how much would they have to pay to make it worth it? Even if he takes all the money made from that, and misappropriates the actual tuition money from somewhere else, I can't see that being enough of a motivation for a millionaire. That would be like Jeff Bezos stealing change from the homeless: is he evil enough to do it? Yes. Is it worth his time? No. If Stephan wanted more money, he'd go back to being a dirty banker, and make some real dough, while also being less likely to actually be caught.