I think of it in a different way:
> Why do people create at all? It's certainly not the most effective route to maximum income. It's a form of connection. Performing is sharing the joy of music and creativity with a group of people who've formed a connection to you through your art.
It's worse. Creating seems to be an effective route to no income at all. Popular entertainment is a winners-take-all market; everyone who isn't one of the few popular artists or performers whose name alone brings in money, have to work hard to get anything at all from their work. The little I heard from various second-hand and third-hand reports from textbook authors, novelists, painters, musicians, etc. suggests that the royalties made from selling their output are laughably low. A big factor in that are the parties in between the artist and the buyers - publishers, labels. Those are some of the "faceless entities" you mention, and they're in a position of advantage over the artists, and they absolutely use it to capture all they can for themselves.
Because of that, to be able to dedicate yourself to your creativity, you have to either have a secondary stream of income (e.g. part-time artists with unrelated dayjob), give up most of control and autonomy (commission work, art-as-dayjob - think e.g. art for videogames), or seek any and all ways of indirectly monetizing your work further.
Focusing on that last part - for musicians, this is primarily live performances and merchandising (self-publishing is also easy today, but so is piracy). But per what I said above, most musicians are starved for money, and this - not greed - is forcing them to be less picky than they'd like. They can't afford to leave money on the table.
The paradox here is that most people - which includes the audience - think like you think, that artists are the opposite of corporate greed, that art is about humanity and not money, etc. Every artist knows that too, and that maintaining this reputation is critical to their income. Between two competing pressures, each artist has to find a point that's acceptable to them.
But this is where Ticketmaster comes in - they offer a way for artists to be more greedy without taking a reputational hit. Their Eternal War with Scalpers keeps the ticket prices up, while all the public outrage gets distributed between the Greedy Corporation and the Scalper Scoundrels.
Not all musicians engage in this on purpose, and for those who do, it's hard to prove. And of course it's just one slice through the complex relationship of artists, public, and countless commercial third parties in between them.