> In some cases, they even have a negative return on investment — meaning degree holders spend more on graduate school than they can reasonably expect to earn later on.

this is easiest to see in things like public education where a Master's degree will net you an additional $1200 stipend [1] though it costs ~20k to earn that Masters[2].

[1] https://4.files.edl.io/bb1d/06/30/21/132300-7b7e7b32-778b-4c...

[2] https://onestop.utexas.edu/managing-costs/cost-tuition-rates...