In the 1950s-1960s, the university system was expanding, in part due to the post-WWII GI Bill. Anyone with a PhD was pretty much guaranteed a decent job. A py

In the 1950s-1960s, the university system was expanding, in part due to the post-WWII GI Bill. Anyone with a PhD was pretty much guaranteed a decent job. A pyramid scheme works well when the pyramid is expanding. It doesn't work so well when the tip of the pyramid is shrinking. If EACH tenured professor has 1 graduate student per 3-5 years, that's nowhere close to the rate at which new tenure track jobs open up. There are some private sector jobs for Math PhDs, but even those have an oversupply.