I do think that there are possibly too many dance and drama courses now, producing thousands of graduates every year many of whom will struggle to find work.
However, for most of these students it is a passion, not a frivolous whim. I am thinking of dance students as I've worked in that industry, I don't know so much about drama students. You don't get many students 17+ who are doing it because of a pushy mum, for the majority they are seriously passionate about it.
I am in touch with hundreds of dance graduates, the majority do freelance project based work, mixed with teaching, lots expand to things like yoga/pilates teaching. A few leave the arts completely but actually not that many. Very few are likely to ever pay back their student loans, they make a pittance but continue on because it is their passion and money is genuinely not that important to them (I am referring to students who did a dance degree, which assuredly exists).
With art, you either are talented or not. Schooling in it is pointless
Sorry, but for dance and music at least this isnt true.