Honestly much of your reply is confusing me and doesn’t seem to be relevant to my questions. This is what I think is crucial:
Just because a file is cached on your device does not mean you are the legal owner of that content forever.
What does being “the legal owner forever” actually entail, either with regards to a physical book or its scan? And what does that mean regarding what I can legally do with the cached file on my computer?
I never said I follow the law, I’m just wondering what the law says ;)