Not to mention if you are a current full time student, you have to swap insurance or housing for education. Heck, I feel like most of that circle should be education.
It's an aggregate over all households. People are students for 4 of the ~60 years of their adult lives, so only 1/15 are full-time students. (Perhaps more, as this doesn't count grad school or two college-educated people getting married and becoming one household. But it also doesn't count the people who don't go to college at all, which is an even bigger proportion.)
