This particular individual may have fallen prey to it. However, I think students in similar situations face something a bit more nuanced than the sunk cost fallacy.
If you accept that middle-income, professional jobs are decreasing relative to lower-income and higher-income positions, then many students with a non-trivial amount of debt are in a trap. For example, say you graduate with a B.A., $120K in debt, and the only job you can get out of school pays ~40K, but low upward mobility long-term (pay-wise).
Your options are (for this hypothetical):
(1) Take the ~40K job with low upward mobility long-term.
(2) Purchase a $120K graduate degree that offers a 65% chance at a six-figure job out of school (and high upward mobility long-term) and a 30% chance of a ~$60K job (and medium upward mobility long-term) and a 5% chance of ending up in outcome (1).
Which is more rational?
Now, we could get into questions of how well this maps to reality, or what the expected value of each outcome is, or how to even compute expected value in a situation with myriad messy variables and reductionist assumptions, etc. Regardless, I think we can say that if income and upward mobility resemble a barbell distribution more than a normal distribution, then we have defeasible justification for believing the following:
(Proposition) A non-trivial number of students face decision traps which lead to a choice less akin to the sunk cost fallacy than a non-confident choice when living between 'a rock and a hard place'.
At times, people will say something about having invested so much already that their decision is pretty much pre-determined even though they're attempting to convey having made a non-confident choice after being stuck between 'a rock and a hard place'.