I have many 3.5 inchers. None of them lost data, either.
Although as a precaution, I long ago copied them en masse to CDROMs. Later, the CDROMs got copied to hard disks.
I gave away my PDP-11 long ago, but not before I copied the 8" floppies it had (circa 1980). But one day I realized I had neglected to copy a critical file. I had the floppies, but no way to copy them. Then I remembered a friend of mine, Shal Farley, might still have an -11. Calling him up, sure enough, he had it but hadn't fired it up in years and was about to dispose of it. I mailed him the floppies.
He fired up the -11, it still worked fine, and the floppies all copied perfectly. My entire box of floppies, every byte.
A big thanks to Shal and his company, Cheshire Engineering.
I just recently went through around 300 floppy disks -- 3.5" HD mostly, but also some 5.25" 360k and a few 3.5" DD. All dating to 1985-1995.
Overwhelming majority of the disks were readable. I have about 15-20 that aren't... and many of them may be formatted Mac 800k which I am not able to read out right now, rather than corrupted.
This even includes many DD disks that were formatted as HD by my PS/2 that just didn't care. Was a slight hassle to get newer drives to ignore the absence of the density hole and read them out.
The bigger problem is that almost all the interesting data I'd want from that era was generally overwritten by dumb stuff. Why keep old papers and source code from when I was a "baby", when a friend was offering a copy of a game?
40 years indicates you're probably using 5ΒΌ" (or larger!) media which is slightly better at media decay due to lower densities.