OP is absolutely correct. Read the library of congress webpages regarding digital archiving. All 'digital' data is held on physical media that breaks.
A HDD will eventually die, and if left untouched the bearings will seize after 3-5 years.
Flash media already discussed in this thread.
CD/DVD/BluRays oxidize and get bit rot no matter how well they are made, or the glue separates and it comes apart. Most SEGA Saturn games have pinhole damage already.
Source code is lost for almost every videogame ever made, data formats go obsolete so fast old archives become worthless, etc.
The only thing that will last past a century is polyester-base film. Vinyl is complete shit however for listening and preserving music.
If society collapsed now, in 100 years no digital data will exist in any format.
However that book on your bookshelf will be just fine. If you want important data saved, make it into physical copies. LOC recommends printing out source code to programs and saving the papers because digital media is so shit at preservation.
Film archives do not digitize old prints, they do this: en.wikipedia.org/wiki/Separation_masters
Think of the physical medium for a second, which is more likely to last longer: developed film (where the 'data' is encoded in the media itself in the chemical makeup of the emulsion layer) or a SSD that is dying from the moment it is made?
Some of the old film companies have existing B&W film produced in the 1800s they still test develop and old negatives, and the stock doesn't decay. (?Kodak)
tl;dr The only thing that will survive the test of time are books and black and white film (photos, film reels, whatever). Digital shit is just a flash in the pan. One good interruption like WW3 in the interruption of supply for electronic media and shit will break before it can be backed up (imagine no HDDs for the better part of 10 years).