This is entirely off-topic re: ebooks, but I, too, have lost data that I'll miss. All of my data on 3.25" drives is likely lost, not to mention most of them have been thrown away. I do oww a USB floppy disk drive that was a gift from a friend that visited Japan (it brings me joy). More shockingly to me is that some early USB drives I own have failed.

The collection my have been careful curated but it was improperly stored. The (onerous) way to "store" them, (in hindsight,) would be to copy each of them would have been to copy them all to 3.25" disk when those came out, then (briefly) to zip disks, then CD-R, DVD-R, Bluray-R, and then also included a drive to read them in this backup, once it became apparent that spinny plastic frisbees were no longer a popular data storage format. Or copied the data to archival LTO tape, going up in number as new standards came out.

Or instead of moving between archival format, the other options is to copy it to hard drive and keep moving to bigger and bigger drives, and have online copies and not offline.

If that all sounds too ridiculous and no sane individual would ever do that: you're right and we hang out on /r/DataHoarders.