Also, you're very much failing to control here: Everyone in your example was in college! Even those hetero dudes you're talking about were likely going to wind up with college degrees.
Also, why wouldn't the gay men be having sex with other gay men? This call out seems weird. Who else would they have sex with? What does this detail provide to your story other than a sense that you seemed to have mentally noted how much sex, and with whom, other people were having?
Assuming your hypothesis is right (and not just a continuation of a stereotype the gay community is constantly dealing with), you have any links to studies that show that people who have more sex get more college degrees? I've got this from 2 seconds of google that would point in literally the opposite direction: https://www.chronicle.com/article/study-finds-more-educated-...