Henry Holt and Co., Walt Disney - at some point they legally ceded ownership of their creative efforts to other entities. I don’t have a problem with that. I don’t have a problem with copyright law supporting that. Are you jealous because you don’t get a piece of the pie? Invent your own mouse and bring it to market.
No. I don’t “want a piece of the pie”. Except that you’ve decide mathematics somehow isn’t a creative endeavor, and we mathematicians should get royalties on people using our results, while authors and animators (and their estates or anyone they alienate their rights to) should get royalties on people using their character, I already have one: the only right I ceded regarding my two papers in deformation theory is the right of the journal to publish copies of the papers in perpetuity. I retained all other rights. According to your theory, if anyone makes money using my results (for instance reproducing them in a book that they sell) I should get a cut, the same way the writer, director and animator of a new Mickey Mouse cartoon are supposed to pay Disney Corp.
You still haven’t explained why the fruits of mathematicians’ creative endeavors (theorems and proofs) are not subject to the same protection as fictional characters or fictional settings.