There are an enormous variety of STEM degrees, particularly the "science" part, that have little economic value relative to the number of people with degrees produced e.g. marine biology. In many of these STEM fields the expected wage is essentially lower middle class because the supply of graduates greatly outstrips jobs.

Not everyone with a STEM degree is a computer scientist or an engineer. If you are one of the countless thousands of people with a low-value science degree then not only are there few jobs at any pay scale but you will likely make more money doing something else in any case.

Anyone who is smart enough to calculate the differential of equations is smart enough to see there's little money in those jobs.

You see this in practice. STEM graduates do 3 things, in my experience. Work in management, work in IT, and work in academia. I wouldn't count on any of having up-to-date science knowledge except the academic ones.