For several decades now, girls have been outperforming boys academically. They earn higher grades, are less likely to drop out, and are significantly more likely to attend college. Women now earn the majority of professional degrees, according to the Hechinger Report, including 60 percent of master’s and doctorates. The growing gender gap in achievement isn’t just bad for young men, it’s bad for women too. Wages for less-educated men are decli…