Comment by ritz_labringue

Harry Potter action figures trade almost entirely on J. K. Rowling’s expressive choices. Every unlicensed toy competes head‑to‑head with the licensed one and slices off a share of a finite pot of fandom spending. Copyright law treats that as classic market substitution and rightfully lets the author police it.

Dropping the novels into a machine‑learning corpus is a fundamentally different act. The text is not being resold, and the resulting model is not advertised as “official Harry Potter.” The books are just statistical nutrition. One ingredient among millions. Much like a human writer who reads widely before producing new work. No consumer is choosing between “Rowling’s novel” and “the tokens her novel contributed to an LLM,” so there’s no comparable displacement of demand.

In economic terms, the merch market is rivalrous and zero‑sum; the training market is non‑rivalrous and produces no direct substitute good. That asymmetry is why copyright doctrine (and fair‑use case law) treats toy knock‑offs and corpus building very differently.