Hard drives break down from use, not from sitting around. We aren’t talking about SSDs which while they don’t break down will experience data corruption over time. It’s not really a gamble at all with mirrored drives.
You’re also telling me things I already know. I already use ZFS. I agree that you should be using something with data integrity protection. Though ZFS isn’t always what you want for archival purposes.
That’s why you use multiple drives with bitrot protection. Modern SSDs and HDDs have protections against bitrot built in, including internal checksums.
If you are running your hard drives once in a while, then bearing failure isn’t really a concern. You probably should be doing that anyway to refresh the data and make sure it doesn’t degrade. Regardless people have had 10 year old drives of older spin up first time. It’s not likely you are going to have a mechanical issue on multiple drives anyway.
If you refresh an SSD once every couple of years it will last decades.
You keep doing this thing where you presume I don’t know about some issue. Rather I know about these things, but they have fairly easy mitigations or are already solved.