The technocratic thinking that caused the college boom pre-dates the Baby Boomers and goes back to the GI Generation and those that came before. Basically, what happened was they saw that one path to success resulted in exceptionally better results (High School > College Degree > Professional Career) and decided to try and maximize the number of people going that path as a way to uplift the country.
Bear in mind, in the mid 20th century the idea that everything in economics answered to Supply and Demand was not as well accepted, and not applied to everything. This was the era that was dominated by Keynesian and Marxist economics and while the Austrians were writing against them, nobody had yet synthesized Austrian economic thinking in a way the elites accepted (Elites HATE Austrian economics because Austrians basically say the best thing government can do for the economy is shut up, sit down, and let people be*).
Boomers actually became some of the biggest critics of Keynesian economics, the first big wave of Boomer legislatures came into office in the early 90s as part of the Republican Revolution and forced Clinton into reducing government control of things ("The era of big government is over"), and it was those same Boomer politicians that opposed GenX Obama's clearly Keynesian economic policies and made up the mass bulk of the Tea Party protests against Obama, which were heavily economically driven.
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* This aside reminded me of one of the best political rap battles ever put on Youtube:
Keynes vs Hayek Round 2. Don't just listen (even though it's a great song) the visuals are also utterly critical in telling the story and note how the Elites always gravitate and favor Keynes while Hayek's main support comes from the common. Hilariously, we even got a test of which approach worked better when Trump became president and took a much more... Hayekian approach to the economy and things grew well beyond what all the elites predicted was the "new normal" under Obama's Keynesian inspired policies... at least until COVID and suddenly everything was being centrally controlled again... funny that...