Out of print / risk of printing books
Although digital can seem to be taking over, printed books are still preferable in some situations and by people in general.
The problem with printing is that there is a risk that, once printed, the lot won't sell or won't sell enough to break even on the cost.
Moreover, when a book goes out of print, people may still want it for various reasons. Regardless of whether or not it is available as a digital edition (and dmany books that would be of interest to historians and people with niche interests are not available online), it would be good in some cases to have the possibility of getting a printed book.