Each country and culture has a different view of tertiary education. In Australia, for example, it is often no prioritized as high as trade labor and it also has relatively high costs of attendance. Much of their tertiary education system is funded by foreign students who pay high premiums to come to the country and get an education. But there was a time (probably still the case today) where being a license plumber would generate more income than a lot of "middle class" jobs out of college. The thing you have to do is factor in the 4 years of lost income during education + the 4 years of lost work experience (the student will come out of college with 4 years less work experience than someone who didn't attend). After you get that back, then any additional income made starts to pay down the cost of the college education. Once that is covered, then you start to earn revenue. The question is for how many years will you have left before you exceed the income of the trades person, and if you are carrying student loan debt for many years, it may be that you never actually do earn more. It seems no one actually runs the numbers anymore on these things, and yet they are the most important economics that any student should know.