I bought a drive a number of years ago with intentions on backing up my NAS. Never did because the media was still prohibitively expensive for the amount of data I was looking to back up.
The only options for this sort of backup are tape, HDD, or cloud. Optical media were never really feasible for backups because they were either too small or writers were too expensive. Supposedly AWS Glacier used them at some point, but you need that level of infrastructure to manage them.
I bought a drive a number of years ago with intentions on backing up my NAS. Never did because the media was still prohibitively expensive for the amount of data I was looking to back up.
I've been waiting for the price to go down.