Musicians will want to make use of what everyone has which is Fiat. Artists knows that whomever, is paying them has Fiat and they're cool with it. They wouldn't want to ask for crypto to avoid limiting people from contacting them or make donations to them because it's not everyone that's into crypto currently.
I believe that most musicians have crypto amongst their asset but they wouldn't make it public
It might be unwise for musicians to openly disclose their crypto holdings. Or at least, let the public know they actually hold crypto. To be on the safe side, it's best for a third-party or middleman to collect crypto payments on musicians' behalf. Yet, it's much easier and convenient to accept Fiat payments directly. Stablecoins are an option, but they do require some technical knowledge to be able to use them properly. I mean, stablecoins work the same way as crypto when it comes to sending/receiving payments. The only problem is that stablecoins aren't backed by the government. You'd have to trust the company (issuer) of the stablecoin doesn't go bankrupt or fails to maintain its peg.
Both crypto and stablecoins are still in their infancy, so maybe things will change in the future. For now, Fiat remains "King" for payments or donations sent to musicians.