This would not be a big problem if the government were not guaranteeing student loans. Most piano, ballet, and tennis lessons have "negative return on investment", but that's fine since people have non-financial motives and are paying for the lessons themselves or having their parents pay.

Colleges should be on the hook for over-selling certain degrees, and charging too much for 'em.

Universities are for training researchers and conducting research. We should stop treating them as vocational schools.