Please understand that copying intellectual property and theft are, legally speaking, two different things. If I build a machine that just makes endless copies of your intellectual property, just because I can, it doesn’t affect your income whatsoever. You don’t get more poor for each copy that’s made.
I agree with you about pirating media that’s not legally available. However, a lot of great content will become unavailable at some point in the future. Making a copy for the archives while it’s possible is a good idea for any media you care about, since there’s no guarantee that anyone else cares.