For the third time: IF you take care of the data, it’s fine in both cases. If you neglect your beloved book for 70 years and store it under a bridge, it’s going to be completely useless as well. The key part is the taking care of your medium.

The taking care of the book for 70y does not involve recreating the book over and over again to keep it readable or keeping a reading machine in working condition (or be able to recreate it). It's an entirely different level of care.

If the medium isn't destroyed, it is directly readable if it's a book, but not necessarily so in digital because hardware and software is needed - just taking care of the original medium isn't enough in digital over centuries.