Agreed, but I'd say these would be artists in the "grey area". They are capable of drawing furry art, for example, and have the choice to monetize that, even though they might have become bored with it.

I was mostly considering contemporary artists that you see in museums, and not illustrators. Most of these have moved on to different media, and typically don't draw or paint. They would therefore also not be able to draw commission pieces. And most of the time their work does not sell well.

(Source: am professionally trained artist, tried to sell work, met quite a few artists, thought about this a lot. That's not to say that I may still be completely wrong though, so I liked reading your comment!)

Edit: and of course things get way more complicated and nuanced when you consider gallerists pushing existing artists to become trendy, and artists who are only "discovered" after their deaths, etc. etc.)