This is why I still maintain a digital music library -- backed by a physical media collection that sits in my real live analog house -- that I sync to an SD card in my phone. In 2018, Bandcamp seems to have solved the digital music sales problem that the iTunes music store never could (DRM-free album downloads in lossless formats for less than the retail price of the CD or LP). Everything that isn't there can usually…
Secondly, I'm a DJ and even if I would not be able to hear the difference, there are people with certain hear impairments in which the psychoanalytic model does not fit. It's my job to bring the best possible sound quality.
But I hardly buy physical media anymore, it's just using up space of something I don't use and with the saved buck I just buy more music :)
My backup is done through git annex and my library is duplicated over many PCs and harddrives - it works quite well and I'm able to carry only a part of the library but still see everything. A simple "git annex get ..." will get the requested files. My girlfriend has my library as well and when I add new files, a quick "git annex sync [...]" will update her copy as well.