I have all my 4k, bluray and dvd discs ripped to .iso (audio discs are another story lol) for backup and archive purposes.
When newer or more efficient codecs get released i can quickly re-encode the lossless video and audio from the .iso into the better format which gives me excellent space saving on my media drives.
Huge capacity HDD drives are cheap and you'll only be writing to them infrequently.