Books seem somewhat unique to me in that the physical product is better or at least different from the digital one, so it kind of makes sense to buy it even if you already have a digital copy. This is unlike e.g. streaming services where the paid service is strictly worse than the pirated one (e.g. no offline, doesn't work at all with some monitors/setups, only low bitrates allowed).

"Better" is of course subjective. Digital is better to me: I can read the digital version on my laptop, phone, or e-reader. I prefer the e-reader, but don't like to carry it everywhere; at the very least I can always read on my phone if that's all I have on me.

I'm someone who used to be a voracious reader. In my childhood alone I would devour paperbacks and hardcovers like nobody's business. My summers were spent destroying the full summer reading list distributed by my school in weeks, and then going to the library to find more things to read. I have had thousands and thousands of physical books in my hands during my life. But I still prefer digital.

I only purchase digital books that either have no DRM, or stripable DRM.