Look, no artistic endeavor needs to make a billion dollars. Even when something does take a billion dollars in revenue, none of it goes to the artists anyway! Music labels and movie studios and book publishers are infamous for creative accounting and bogus contracts and outright lies to fuck over almost every person that actually contributed to the art. They're worse than politicians. It's all there to funnel even more money to people who are already rich. If you put artists on basic income you're not paying them any less, you're not losing anything, 99.9% of them come out ahead of where they would've been if they'd sold their work for money. Maybe add a couple more nines to that list. For every multimillionaire movie star or generation-defining author there are literally hundreds of thousands of artists just barely scraping by. Capitalist art only benefits the leeches.