Good post. I initially made a somewhat long comment but finally decided to delete it because, well, it simply sentenced the same questions you ask, namely:

Do you think, after having had a headache, that the headache went away only because you took a pain killer pill? Can it also be that it went away because you think that a pain killer will kill your pain?

I agree, and we may never be sure about that.

Have you made the habitual experience that all pain goes away eventually? Like you cannot laugh for hours in the same way you cannot cry for days, it'll all go away.

100% true.

Everything else you talked about reminds me of recent conversations I've had about this very topic, but I won't bring that up here because I don't think it's worth it, and in short, I agree with you.

Sorry I can't add much to the topic you brought up. Cheers!