The PhD graduates who cannot find professor positions may experience underemployment, such as working at a job which does not require their education.
Many commentators, including human capital theorists and proponents of positional consensus theory, assert that there is a tightening relationship between education, jobs and rewards, and that in general, the more qualifications you have, the more employable you are.
These ideas have informed policies to widen access to educational opportunities with the goal of promoting equality and maximising efficiency according to meritocratic ideals.
Taking this relative quality of qualifications into account, it can be argued that widening participation in higher education and qualifications will not necessarily deliver the rewards that human capital theorists have suggested, if the number of graduate degree-requiring jobs does not increase accordingly, and will instead lead to academic inflation: According to this perspective, if everyone holds the same credentials no one gets ahead and the result is a kind of social congestion around sought-after jobs.
Brown[1] describes this as an "opportunity trap" since few individuals are able to opt out of the competition for jobs and most are compelled to strive for credentials in order to be considered employable.