I don't know how else to explain it. It doesn't feel the same to have my contributions smushed into a linear-algebra machine? For me, the incentive was the idea that my contributions might have directly helped someone. That absolutely does not feel the same when I think "My answer has modified the back propagation of a Machine Learning training run."

It doesn't have to make sense to you - I just believe that I'm not exactly alone in this thought.

Now apply this to Art, free stories, writing etc. It feels bad to have your free contributions hoovered up and monetized. It doesn't feel particularly fair or ethical to me. And it'd make me double think before making something free and publicly available.

Understood, there's certainly nothing invalid about your point of view here. It's just not one that I personally can come to terms with.

I've spent a lot of time in your shoes, wasting time on busy-work needed to accomplish a larger goal (and absolutely sharing the results freely, over multiple decades)... and I don't miss that part of it one bit.