I keep mine for as long as I can really... some files get lost over time or between transfers or during organizing, but I still do my best to keep the source files safely archived on my drive!

After all, storage is cheap and even after so many years of drawing, all my art files are around 50 GBs or so.

Interesting... Personally, I don't trust the hard drives here. They seem prone to failing unless you go for a high spec one. Mostly, I just want to keep my PC's storage under 50% full and with the size of leisure bloatware (Games) these days it's getting difficult to both store a few on and keep backups of the important art stuff as well. Any particular reason why you keep yours around?

Personally I have a separate drive for my games, since they do get pretty big these days. And I still delete older games frequently to make room, thankfully Steam keeps settings/save files stored in their cloud if I want to play them again in the future.

Art files are valuable for me, sometimes because I want to check back and see how I did certain details, sometimes I remaster them with my new skills, sometimes it's just nice to have an archive of all my works. I suggest keeping them somewhere, even if you just throw them in a folder and simply organize them by year. They're not too big after all.