One theory I’ve heard is that a lot of white males can get decent jobs without college degrees, so they do so. Members of other demographic groups, though, are really screwed if they try to enter the adult workforce without a college degree. So they’re more motivated to get one.
That's an interesting theory, and it probably explains some of the decisions made by many people I know. Is this a theory you've just heard casually mentioned or has there been actual research on this?