They chose teaching college. What they didn't know, when they spent all those years earning degrees that are useless for anything else, is that most college instructors are condemned to slave away as untenured adjuncts working at piece rates with no benefits, job security, or chance at ever getting full-time pay. Meanwhile, academia is full of minority political officers who earn anywhere from $80,000-150,000 plus benefits, merely for harassing the working folks.
(When I went to grad school, my excuse for not knowing how the system worked, was that I'd just come from spending five years abroad. It was also a long time ago, and our system of higher education was not quite as transparently corrupt as it now is.)
Just as people who get degrees and advanced degrees in history, or english, or african-american studies and what not. They knew in the beginning that those degrees would not lead to lucrative careers.
As was said in the beginning, people make decisions and those decisions lead to their financial situation.