The economic advantages of fraternization

It’s often used as an advertisement for them that fraternities and sororities are advantageous because they increase business opportunities for their members, but is that really the case? Some enterprising economics grad student could get a thesis out of answering that question. Take fraternity/sorority members and nonmembers, correct for socioeconomic status, age, religion, nationality, and the other usual suspects of economic drivers, and see who earns more over their lifetimes. Even more interesting: lump all professions together, then separate them out. If being in a frat makes you richer, is that because of your business contacts, or because being in a frat makes you more likely to get an MBA instead of an MFA?