The Sumerians wrote on clay tablets. The egyptians put hieroglyphs on stone and papyrus. What ancient people put on stone and clay has a chance of lasting through the ages. We've even stumbled across helpful bits of stone that help us translate between languages.
In the digital age things are much harder. It's hard enough to access a document created in some now obsolete program. It's a matter of digital preservation and fighting digital obsolescence.
Still not convinced it's a problem to preserve digital information for the future? How about this simple question... can you still buy a computer with a floppy disk drive? And what type of floppy disk drive? The 3.5 inch ones in the hard cases or the older 5.25 inch disks? What about the 8 inch floppies?
It's a much bigger problem than just a few different sizes of floppy disks. Take a glance at some of the ways we stored digital data at the Lost Formats Preservation Society page. Glancing over the monochrome outlines of old storage technology it makes you wonder how many digital documents have already been irretrievably lost.
Of course you could also play the geek cred game of working through the list and finding out how many of those formats you've used at one time or another. My LFPS number is 18. If I include a couple of formats that aren't on the LFPS page I'm up to 20.
And the LFPS list doesn't include any type of internal hard disks. They only cover portable media. But old hard drives are lost formats as well. Disks that I pulled from original IBM PCs can't be plugged into any new computer. The number of different hard drive types is staggering.
The more I try and wrap my mind around digital preservation the more I think it will be easier for archeologists in the centuries to come to know about the early 1900s than it will for them to dig into the details of the early twenty first century.