Hi there
A lot of people here back up to NAS boxes -- but remember These CAN fail as well (or at least an HDD can).
So I do suggest that you actually backup the stuff on your NAS from time to time -- you might NEVER need it but who knows.

NAS boxes (or things like Micro servers) are quite cheap these days -- re-installing music, re-ripping CD's and DVD's and possibly re-torrenting (assuming the stuff is still seeded any more) isn't worth the hassle.

I now have a Backup Box -- once a week I simply just copy the HDD's from NAS1 to NAS 2 --- job done.

I'd advise people to start thinking of things like this -- Backup is always good but you do need more than one copy. Don't rely 100% on your NAS box thinking you are 100% safe -- you probably will be but you never know.

Again re-creating data if you have this sort of failure might not be a problem - also if you have your stuff stored in the Cloud but if you've got several TB of music, and video then the Cloud won't be a feasable backup mechanism.

I'm actually not a big fan of commercial music streaming services or commercial digital downloads-- quality too low etc. I like High end FLAC rips of SACD's or even standard CD's - especially classical music. Things like Spotify are OK for PUB Background music or music listened to with cheap bud earphones but not for decent music listening.

For Video -- streaming is fine but I often like to watch stuff again and a lot of streaming services only make it available for a certain period and riddle content with DRM so I choose to keep my own.