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.
They might not be our individual personal copies, but they’re there, actually accessible.
To your point, I am strongly for enforcing DRM clearing after the copyright expires or the entity owning them goes under (it should be required by law IMO). I also think collectively we have a fighting chance to preserve copies as long as they’re free of DRM.
I don't know if they're from 1969 - but I do own a few punch cards...
The point is that it's actually fairly hard to beat acid-free paper for archival storage.