There is a ....disturbing....culture amongst minority groups. It's most common amongst very poor urban black populations, but affects all groups.
They value street cred over education. I see it every day. Kids throw away huge opportunities to leapfrog 2-4 years over their peers, through things like career tech programs and early college courses (that are FREE). Instead they screw around, and only care about what their crew/gang/group of friends is doing. they see education as THE MAN, and think they are resisting influence by ignoring it.
then you see the students that do try, and get bullied for it. You see bright young black students bullied relentlessly because they do their homework, or listen to the teacher, or refuse to take part in shenanigans. It's depressing, and very common.
Like I said, it affects all groups, but black populations in school are most affected, with hispanics to a lesser degree. It's much rarer to see that in Caucasian or Asian students, quite the opposite. And there is only so much the school can do to help, since this extends outside of school, and deep into the communities themselves.
So I actually believe Zuck here. If the students in high school dont care and barely graduate, how many of them will come to their senses, shape up their life a bit, and actually apply to college or to a trade school. And of those that do, how many will actually be accepted, amongst the competition from tons of good students that didnt screw around and hang out with the wrong groups? It's a self-serving cycle, that keeps repeating itself constantly.