Perhaps it is an outdated idea, but I have always considered playing a concert much more about sharing the music at hand than about "me" playing the music. When I go to a concert, I go to hear the music. The person playing or the people playing are responsible for allow the music to sound the best that it can sound. When I play a concert, my aim is to play the music as well as I can, and to communicate its emotional content or what I believe is its emotional content to the audience. I try to play in tune, in rhythm, and with a good sound so that the music can be alive for everyone in the room to share. Greatness is not the object, but pleasure is. When I'm playing with a group, I do my best to blend with my ensemble-mates, as well as to play in tune, in time, and with a good sound. It isn't "about" me when I'm playing. It's about the music and about the community that it creates.
It isn't even "about" the composer. I know, from personal experience, that being a composer means that you take responsibility for putting pitches, rhythms, and sometimes words together in ways that make music. Once those elements are in play, the music no longer belongs to the composer (unless there are pitches, articulations, and notation issues that need to be fixed after a performance). At best it becomes a vehicle for expression for the people playing, and is "about" the relationship between the pitches, rhythms, sounds, and the musicians. If I happen to have the good fortune of writing something that people enjoy playing and that people enjoy hearing, I have done something successful. If I can do it more than once, I'm extremely fortunate.
I don't believe that a piece of music is a vehicle for the ego of the person or people playing, but I have observed everything to the contrary during my musical life. Perhaps I first noticed it at Juilliard in the 1970s, but I'm sure that it has been around much longer than that. Musical ego, distasteful as it was to me at the time, was generally accepted as a good thing. Its omnipresence led me into a revolt against Western thought. I believed that musical expression was the major aim of music making, and that technique was what made it possible. I still believe it. I also still believe that the ego gets in the way of musical growth. Worrying about what people think can inhibit creativity and expression, especially when people, for whatever reason, don't communicate truthfully about music.
We all have musical ego to some degree. If I play something badly, I feel ashamed. If I play a concert and nobody shows up (it has happened), I feel hurt and insulted. If people don't acknowledge my existence in my musical community, I feel hurt (it does happen).