I used to do floppy disk data recovery as a service for students at college. Roughly speaking, we helped one student out every three hours, out of 2,500 students, during busy hours. Based on the rates and hours, I think it would come out to something like 25% of the student body, each year, coming to us with a data loss incident involving floppy disks.

YMMV. I’m sure a lot of people were shoving these things into backpacks, and this was post-2000, so the quality of disks for sale was poorer than it was in the 90s and 80s.

I’ve also (since then, for myself) repaired drives. The drives fail because they’re mechanical and have motors, and anything that moves or has a motor in it will need some kind of service. Servicing a floppy drive requires specialized equipment which is hard to find (or requires a lot of patience—it’s possible to repair a floppy drive with just a screwdriver, but it’s not fun; guess how I know?)

3.5" floppies were still common while I was in college. I have distinct memories of copying a project to a floppy in my dorm room, popping the disk out, walking next door (literally next door in the dorms, not even going outside up or down stairs or anything), popping the disk into a team member's PC and the project being gone. We laughed it off and chucked the disk in the trash and got another. Project wasn't lost-lost since I had a copy on my hard disk. This was also the era of the 100MB Zip Drives, which I also had in my PC and thankfully all of our lab PCs had, too. That's what I normally used for all of my day-to-day file transfers of any real import. I still have my zip disks, but I seem to have lost my zip drive, so no idea if the disks still have any data on them.

Sure, but what are the odds they're using these rather than HD 3.5" disks purchased from whatever new old stock they've been able to source over the past 20-odd years?

and how many bits have rotted on those?