That might be part of it, but I am pretty sure Vassar also refers to the fact that a lot of young men with the ambition and curiosity to do better spend the vast majority of their time getting more skilled at their strongest skill because that is what they perceive as the optimal path to economic security and status and the fact that academics are encouraged in this severely non-optimal path (in part because it is convenient for academic institutions and advantageous for ambitious academic bureaucrats to divide human knowledge into specialties and subspecialties).

If these young men could relax more and not worry so much about their own status and economic security, they would tend to heed more their natural human sense of curiosity or their more playful social impulses (including perhaps altruism), which are probably all better guides to what to learn next than the desire to advance in the academic status hierarchy. In other words, a burning desire for status, particularly status that comes from a reputation for having some refined skill or expertise, is not as reliable a guide to self-actualization as it was in the environment of evolutionary adaptedness. Well, that might not always be true: for example, not working towards the right kind of status can prevent one from having access to the kind of friends and mentors who can best help one to learn. But it is certainly true that a lot of young men (and perhaps women, too, but I tend to think that the fear of social disapproval is a bigger problem there) do not take advantage of the social opportunities for learning that they already have (and limit their educations in other ways) out of a fear of not having enough status or income out of not having a good enough reputation for skill or expertise.