So there's a lot of considerations and a lot of different systems at play depending on where you're based. For example in France and Belgium (and probably other places), most music copyrights are handled by a State-sanctioned "non-profit" called SACEM/SABAM which has administrative fees and execs paid with 5/6 digits salaries, and arranges the money to be funneled through over a dozen other "non-profits" (who have the same kind of setup). This is not exactly a monopoly because by law you can still manage your copy "rights" individually (collective vs individual management) but then everything gets more complicated. There were talks about a decade ago of a europe-wide, cooperative collective rights management association, but i don't know what happened to that.

Anyway, under this system, there are a lot of inequalities. According to official SACEM statistics, about 2/3 of their registered artists (who pay for membership) never earn a single cent every year. And in 2011, only 150 artists (less than 1%) earned over half of all redistributed revenues... then again, the amount that is being redistributed has been severely punctured by the execs/administrative types who get paid no matter what. The highest french financial authority, la Cour des Comptes, has many official reports over the years about the misbehavior of SACEM & friends and how they swindle artists through legal though dubious schemes (moving money around many orgs, each applying administrative fees until there's nothing left). So that's for "independent" artists under collective management.

Then there's artists giving away their rights to publishers/editors. They will be pressured to accept a small percentage in exchange for having their album/book/movie published "for free". But they've essentially sold their soul to the devil. If their art doesn't bring a lot of money, the publisher has essentially lost nothing. But if it does, then it's making tons of money, some of which will pay for the same kind of capitalist bloodsuckers (execs/investors), and the rest will pay more well-known artists who had a position to bargain for better contracts.

But even if your art fares well, your publisher may decide to stop publishing it, and there's absolutely nothing you can do about it. Under some jurisdictions you can bargain with the publisher to buy back your rights (that's gonna cost you some serious €€€), but under others you're simply left powerless because distributing your own production is now a violation of the publisher's copyright. How fucked up is that?

Then there's live performances. If you're a more-or-less unknown artist, all the money you're gonna make is with a live audience. But once you've sold the rights to your music, movie, or theater piece to a copyright vampire, then you have to pay them off to play your own works and you'll only retain a portion of whatever should have ended up in your pockets.

There's plenty of other aspects to consider and i'm not familiar with all of them as i'm not an artist myself, but i have enough artists in my close circles who've made the mistake of dealing with copyright, editors and such nonsense and will never do that again. I don't personally know a single artist who plays by the capitalist rules anymore because they were all fucked by the bigger fish. Now my friends all either publish free art (copyleft) or do pirate art (zero fucks given for copyright).