That’s an interesting take. The logic is apparently sound and the conclusion follows.
Is it fair? (Is it supposed to be?)
I would personally want royalties for my content being shared, but if I can’t enforce that through some type of mutual contract, I would likely need to increase the price of my “initial sale” to cover my potential losses if others buy my work from each other, rather than from me.
That said, there’s something “icky” about the idea of someone putting decades into developing a skill set, creating something that others value, and then selling that piece of art (in the music example) to someone who can then profit off of the artist’s work by doing little more than burning a cd.
Perhaps it’s logical, and unenforceable, but still unethical…