Men wanted to be strong. One way to be strong was to be knowledgeable. In so many areas, it was not possible to be knowledgeable without getting a Ph.D. and doing a postdoc. Guns and hunting provided an out for men who wanted to be know-it-alls but who couldn’t afford to spend the first three decades of their lives getting up to speed on quantum mechanics or oncology (Neal Stephenson, Reamde)