I have bought a kindle, upon which are stored many books. I have also bought many physical books. Have I purchased any kindle books? Well, only if they aren't

I have bought a kindle, upon which are stored many books. I have also bought many physical books. Have I purchased any kindle books? Well, only if they aren't available in physical form. I am confused by people who believe that things on the internet are any sort of permanent - or private, but that's another matter entirely.