The question of college (university) education is complex, but not well explored in this article. First of all, I'm not aware of anyone who thinks going to university "makes you smarter." University is supposed to provide (i) an opportunity to acquire knowledge, and (ii) an opportunity to enhance one's ability to perform coherent thinking. In other words, university can help cultivate inherent intelligence but not significantly expand it.

Secondly, there's no such thing as "a college degree." There are STEM subjects and liberal arts subjects. Those who study STEM subjects usually earn a great deal more than those who focus on "movie studies" or "sociology." This is because there's strong market demand for people who can engineer things, and very limited demand for people who can utter relatively low-value opinions on matters of trivia.

In an ideal society, access to university would be based on merit (as is the case in Europe) and not on alumni preference (as in the USA). But as the USA is a Victorian-age society in so many ways, it's not surprising that social mobility is restricted. It's a problem that exists outside the academic context and so can't be solved easily within it.

One large issue is touched on but not explored: why so many parents discourage (or fail to encourage) their children to seek higher education in subjects that will be remunerative post-graduation. Again, this is an issue that can't easily be addressed by educational institutions themselves - especially when there are strong social pressures against college education.

In Europe, the idea of a university degree being a signal that a person is of adequate intelligence has largely faded and employers are now far more concerned with the nature of the degree (STEM or not?). Perhaps one day the USA will get there - but it will require significant cultural change.