"... the only reason a smart and motivated person doesn't go to college ..." You seem to think being smart and motivated is binary, which of course they aren't

"... the only reason a smart and motivated person doesn't go to college ..." You seem to think being smart and motivated is binary, which of course they aren't. They are continuous. You compare people who are barely smart enough and barely motivated enough to go to college, against people who are barely not smart enough and barely not motivated enough to go to college, to reduce bias. On the other hand, this does raise an interesting issue of inhomogeneous return to education. It is possible (even probable) that return to education is not same for groups with different abilities. It may be the case going to college is a very good deal if you are not very smart, but not a good deal if you are very smart. I think economists are actively researching this area.