I'm glad I never thought about that when I was working, because it might have ruined it for me. I loved being a manufacturing engineer. Although I was not working for myself I had a lot of autonomy because my boss trusted me. I never ran out of challenges. I get what you are saying but only in part. I don't understand why you think you can't want the things you need. Maybe I have never been close enough to the edge to know. I might want cheese and crackers, but I don't need them.
Music is something I both need and want. Music is what I mostly do in retirement. You could say I need it because without it I might spend a lot of time moping, which would not be emotionally healthy. As it is enough of my time is taken up performing and preparing to perform that I don't have time to mope. There is no economic necessity for me to do it. I do it because I want to, but I would also say I need to. An acquaintance of mine who is a dancer says something similar: That she NEEDS to dance. For her, without dance there is no life. For me, I agree with Neitzche: "Without music, life would be a mistake."