Reagan gutted education spending.

But also the bifurcation of blue vs white collar wages really accelerated through the last 40 years. That is the spread between what my dad made working at a record store vs the professor/admin staff/etc at his college made increased tremendously. Think about it - minimum wage at federal level has only doubled in the last 40 years, while some quick googling looks like professors make 5-10x what they made 40 years ago (as most white collar has).

Plus all the discussion about the bloating of college non-teaching administrative staffing.