People might not be smart enough to study at a college level, but people are smart enough to learn a new trade. During the Depression, technical correspondence schools flourished.
About 29% of adults over 24 are college grads and about 1% have advanced degrees. Only about 4% of people with average IQ (100)or lower have college degrees. It seems like there are a lot people who can’t handle a higher education (college, at least). As to learning a new trade, apparently there are a lot of people who aren’t disciplined enough to complete such training.