Quite a few companies provide pdfs of rulebooks alongside dead tree copies, which I’m very fond of. I love having a physical book to leaf through, but for games that I’m playing digitally, having a pdf to pull up on a screen is very convenient, particularly since the copies of books might not be accessible.
I tend to have a collection of physical RPG books that includes systems that I know I’ll never get to the table, bought for the enjoyment of the production. I would never buy a digitally copy by itself unless I was actively playing that game system.

