You're confusing ownership of media with ownership of copyright. I'm not suggesting that I can buy an mp3 and reshare it (or the same for an ebook), that's a violation of copyright. I've never suggested that buying them lets me remove DRM, re-share, etc. It's a strawman argument that you and conciselyverbose seem very attached to, but not an argument I'm making.
Ownership is not strictly limited to physical items, and I'm very curious why people think it is. There's significant outstanding case law precedent that proves that ownership can apply to digital files as well.
https://scholarship.law.wm.edu/cgi/viewcontent.cgi?article=1478&context=wmlr
Case precedent and law proves you incorrect. Fixed copies of digital assets have repeatedly been proven to be capable of being "owned". There is no requirement that an item be a physical, tangible good in order to be owned. I don't know where you're getting your information (because you refuse to cite it), but it's incorrect.