physical – How long can I reasonably expect my external USB HDDs and memory sticks to last?

I have a number of external USB HDDs (nearly all of them 2.5″) in my fireproof safe. They are between 7 and 9 years old. (For a period of two years, I bought one almost every month until I had enough for me to feel as if it was not logically possible for all of them to die on me at the same time.)

There’s also a bunch of USB memsticks, not much younger than the HDDs.

I take them out on a rolling schedule and sync new data to a couple of them from my main computer, then put them back. It’s a chore, but I pride myself on not willingly uploading my data to some “cloud” storage. (One would have to be a fool to assume that they can’t, or won’t be able to later, break current encryption.)

For years now, I’ve had a nagging feeling in the back of my head that I should be replacing the old ones, or at least prepare a couple of new ones to take their place when they inevitably die on me.

Other than the purely practical problems of cost and getting them here (long story), it just feels weird to me. This might be a sign that I’m getting really old, but it feels like I just bought these disks. They certainly don’t feel almost a decade old! Furthermore, I’ve barely used them according to myself. They’ve mostly been resting in their cozy safe, only regularly getting any “action” in the form of I/O. It feels like I’ve not been “wearing and tearing” on them nearly as much as would be the case if I, for example, was some kind of GoPro action adventurer who has a backpack of HDDs with him on his wild trips into the mountains, where he constantly transfers large video files and exposes them to heavy impacts from rocks and the ground and whatnot.

I have seen and heard absolutely zero signs of them starting to die on me. I don’t remember how long the warranty was, but I suspect something ridiculous such as 2-3 years or something. I cannot imagine buying a hard disk which dies after 3 years. I frankly feel as if these are going to last for hundreds of years at this pace, but who knows? Maybe all of them die on me now, and there goes all my data… A frightening thought in many ways, given my empty existence.

On the other hand, if this were the year 2000 and I had a HDD from 1991 (-9 years), I would’ve seen that as ancient back then…

Is there a non-hard disk company-sponsored report or general advice for how long these things can be expected to last in reality?

There’s also the problem of barely any physical space left inside the safe to put any further disks, so I’d ideally have one of them die on me, then replace that, then another dies, and I replace that, etc. But what if they all go at once? Planned obsolescence?

Everything always comes down to money. I just cannot afford some kind of “tape system” for long-term proper archiving.