On Quinn's manipulations inside HOTs. A few thoughts. Keep in mind that Quinn is a sophomore (second year in college). That means she hasn't been building this "shadow business empire" for very long, definitely not since day one of joining HOTs. Definitely not for years. She needs time to scout out the situation and decide who's right for her business.
Drug circle.
Initially involved: Quinn and Riona.
Patron: Buddy, Rox criminal partner
Clients/informants: Tommy and Rusty, Dawe, the dude from preps, Heather, MC in Quinn's path since Ep. 10., Sally, Lily and the Pink Rose girls, Vinny.
Likelihood of Reveal: Low to begin with until Quinn started her stupid expansion and turf war with Vinny. I don't think HOTs will be unaware that Riona is missing.
Prostitution circle.
Initially involved: Quinn, Riona, Sarah and Mel.
Camila and Mona joined in, Mona jumped off and almost ruined Quinn's entire conspiracy by starting to talk.
Patron: Stephen Burke.
Informed: MC from the very beginning (it was stupid of Quinn to tell a guy she barely knew that she offers sex for money - that part of the game is really poorly written, I don't believe that Quinn is that stupid), maybe some college guys who use the girls for sex know about it. Of course, game will not say anything about it, DPC avoids sexual interactions of MCs partners with other guys. But here the information leak is possible.
Lily is also aware of this, as well as about drugs. In general, Lily is possibly the smartest character in the game, with her intelligence sheyou should go to work in the Mossad / CIA and not study to become a doctor and really, she is much smarter than Sage. Probably on par with Bella.
Next, a potential leak - a rumor about a free tuition. Because it exists and the way to get it is through Stephen's bed. Mona's fire was put out by kicking her out, but then Maya comes and continues to blab about it. I'm sure that Sage will start thinking and looking for the source of rumors. Who could spill the beans? Camila, for example. She's not thrilled with what she's doing and could hypothetically vent like Mona. Or Mona could come back to the scene, accusing Stephen of sexual harassment and corruption at B&R.
At the start of the game, Quinn had a pretty good cover for her business, the chances of a leak were minimal, and it's hard to blame Sage for being stupid for not noticing anything. But with Quinn's management, her impulsive and short-sighted decisions (Chess is not real fucking life, Quinn!), her cover could collapse at any moment. It worked for a while, but in the long run, Sage will have more opportunities to find out the truth, or perhaps Quinn will be exposed in another way.