I would say this is definitely true for big-label musicians. For independent or smaller-label musicians, they still have a large upside potential from certain retailers, like Bandcamp [1].

If you really care about them and they're listed on Bandcamp, it's pretty trivial to sign up for email announcements at an artist level, so you don't miss an opportunity to support them financially whenever they release new material.

Many big musicians don't even have bandcamp accounts, which (1) amazes me (2) implies that they make most of their money through other means, e.g. touring, private performances, etc.

[1] From their website: When you buy something on Bandcamp, 80-85% of your money goes to the artist, and we pay out daily. The remainder goes to payment processor fees and Bandcamp’s revenue share, which is 10-15% on digital items, and 10% on physical goods.