I will be soon building a file server where I will be using raid (idk which one yet) to prevent losing files in case of disk failure. I will also be using a disconnected from the system few TB hard drive to make sure I don't lose my data in case the system goes wild and deletes everything.
I created my first email account in 1999, and it's the one I use for just about everything to this day. A couple of weeks ago I got fed up with constantly reorganising it. No number of rules or folders really solved the problem. There was just too much shit in there, and I have too much shit in my brain as it is. I deleted all of it. Saw a few flashes of emails to my childhood friends, from my first girlfriend, deceased family members. For a split second I thought "shit, no, these are my memories". But no. Not anymore they aren't. You're free.
I don't usually delete stuff on purpose, but I am not as diligent as I "should" be about backing all my data. Sure, I back up the most important things, but the rest of it I won't really miss if it gets deleted.
For example my Bookmarks/Saved Posts/Watch Later/Read It Later lists, they sometimes get deleted when I move devices and I don't bother restoring them even when I can. Most of the things I add to those lists I know I am never going to read/watch. I add them anyway just to be safe, but I don't feel bad if I don't ever get to them. There's only so much time in this world.