Composers are far less well off. The very famous American composer Philip Glass had to work at various menial jobs (driving a cab, moving furniture, plumbing) until he was into his 40s when commissions began to be enough to barely support him.
The situation seems to be that there is a lot of money in visual arts, but a lot of expenses in performing arts!
As I say, I have puzzled over this and never come up with much of an explanation other than rich people like to buy things they can hang on their walls. But Ann Althouse put up a post the other day that offers a suggestion, The Art Donation Tax Evasion. You need to read the whole thing, but the idea is that the New York Times evasively describes a long-standing strategy for avoiding taxes that depends on donating art to museums at inflated values. But the NYT commentators are on to it:
"Ah, the good old-fashioned donation evaluation for taxes. The wealthy have been doing this for a very long time. Museums are there for this very reason. To deposit overly valued art pieces in lieu of a tax deduction. Same goes for property, buildings and other funding to arts, medicine and pet projects. Art is tricky. How is it exactly evaluated? And by whom?"Could this be part of the reason that prices for visual arts seem a little high?