I think for art it can be pretty touchy… Like, I know a fairly succesful scottish author, and he absolutely hates the question, even though it’s usually pretty innocent because it’s like “what value art”- he rates success on completed work, satisfaction with that work, reviews, publications, events, and yes sales but he doesn’t like it when people rate his success and therefore his books based on his “salary”.
I think most people who ask are just curious though- hey, you earn a living doing that? Nice one!
Sort of similiar- one of our students turned professional athlete a while back and got a sponsorship deal. Absolute dream come true, for him, and all anyone (outside of the sport) says is “What does it pay”. Like he was sat down choosing between a job in an office or a job in his sport based on the salary.