"Researcher L. David Mech, one of the primary creators of the Alpha male hypothesis for wolves, later found additional evidence that the concept of an Alpha male may have been an erroneous interpretation of incomplete data and formally disavowed this terminology in 1999. He explained that it was heavily based on the behavior of captive packs consisting of unrelated individuals, an error reflecting the once prevailing view that wild pack formation occurred in winter among independent gray wolves. Later research on wild gray wolves revealed that the pack is usually a family consisting of a breeding pair and its offspring of the previous 1–3 years.[16]

Researcher M.W. Foster investigated primates and found that the leaders were more likely to be those who did more for those around them instead of being determined by strength. [17]

In humans, the concept of an alpha male was challenged as being largely nonexist as per an article by Dean Burnett, who found that human leadership roles vary wildly based on the current social context, and traits attributed to an "Alpha" might be exhibited in one scenario, and traits attributed to a "Beta" might be exhibited in a different scenario by the same individual. [18]"

Wolf behavior is mostly irrelevant in that context.

By looking at those students, you attempt to control for "interest in joining a frat" as a variable, and look at the outcomes for people with equivalent interest who either did or did not join a frat.