The Signaling model of Education

What does college really give students for tens of thousands of dollars? Probably, mostly signal that you can do a good job. That you have the personality traits to succeed, mostly. Although, what about connnections that you, probably, couldn't get if you weren't at a institution? Though maybe you can nowadays through the internet? Also, I would assume practice matters.

Teachers though do seem to matter in K-12 though. Though they don't seem to get better with more credentials or more tenure (past the first three years). The key point is

What we see is that the difference in teacher effectiveness is largest within any school as opposed to between schools.

So, it's not JUST innate ability, because why would kids in the same neighborhood/school have larger variation in (testing) results then the average kid between two schools. Of course, maybe testing results aren't the correct target to measure students' success.