You can also lend the backup to someone, as long as only one copy (backup or original) is in use. This is the principle that libraries use, when loaning DVDs (some backup the DVD so the original isn't damaged). Libraries exist because of the same fair use rights to copyrighted material that you enjoy.
Copying copyrighted material is not (always) a violation, and copyright violation is not theft
. These are emotionally charged words, intended to make the violation seem more severe than it is. It would be like calling the MPAA and RIAA storm trooper ax murders
, when in reality they are just technophobic corporate entities trying to coerce as much revenue from you as possible for their stock holders, using an antiquated business model.