If you drive down my friend's neighborhood in North Virginia, you see house after house of moms with law-degrees, math degrees, engineering degrees, most with Masters, who said "fuck working" after 5-10 years and decided to become stay-at-home. All with substantial student debt that they didn't work long enough to justify.
The number of women who WANT to work is a lot lower than everyone wants to admit. And when they see the option to leave the working world, many of them take it. So much education that just gets wasted when they realize that having a career is not nearly as fulfilling as they have been led to believe.
If I won the lottery tomorrow, my first thought would be "sweet, we can afford a third kid!"