It is trivial to copy all of Wikipedia to a USB drive. The entirety of published books in the world would fit in an off-the-shelf hard disk under your desk, ready to be duplicated endlessly with zero loss. Now compare that to the sheer amount of human history and knowledge that has been lost through the ages due to wildfire, flood, wars, politics, negligence and every other force imaginable.
Not saying that digital storage is perfect, of course, but asserting that a physical copy of a book in a library somewhere is safer and more accessible than bytes on the internet is ridiculous.
The problem is not only that of preserving the data, but also accessing it.
We can read manuscripts and tablets produced millennia ago, but are already running into difficulties accessing digital media published in our lifetimes.
E.g.
Compare the Domesday Book with the Domesday project:
Not saying that digital storage is perfect, of course, but asserting that a physical copy of a book in a library somewhere is safer and more accessible than bytes on the internet is ridiculous.