Unpopular opinion time: I'm torn as to where that theft line is.

If a turn of phrase in Lord of the Rings inspires something new in me, do I owe royalties to the Tolkien estate?

The stories on FanFiction.net are derivative by definition — is it theft? I love "Harry Potter and the Natural 20", a 4th-wall breaking D&D and Potter universe mashup story (seriously, it's hilarious). Does that story owe royalties to Wizards of the Coast and (ugh) JKR?

Maybe those are super transformative. What about opinion pieces where the author redigests information from all over, many paid writings? Are they selling the original authors' product, even though restated?

Maybe it's ok if they paid for the subs. But what if it came from free library books?

My wall has a bunch of art from artists at SDCC. I'm looking at Spider Gwen; Thor, Iron Man, and Mjolnir Cap charging into battle; Kaladin and Syl before the Stormfather; and a map of all the places the Gaang went in ATLA. Those artists all ingested the original work to make those derivatives; were they not allowed to make them if they borrowed their friends' copy?

It feels kinda wrong to vacuum up public data to train models, kinda? But I don't know that I can fairly call it immoral without condemning all these other things I think aren't immoral. I kind of want to, but that'd be really inconsistent, and that's profoundly frustrating in its own way.

It's messy and complicated and I think the gut response of most people isn't actually a reasoned one.