Pretty much the only books I buy are college textbooks. It makes no financial sense to buy digital. (It is barely cheaper and usually better to buy a used textbook and sell it back)
But for a few terms now, I've been able to find many of my required textbooks online for free. (Thanks, Google)
Other books? Eh, I go to the library. Usually, that means it's physical access. (I'd prefer digital, but no choice) I don't buy books unless I have to for a course (and I can't borrow it from the school's library).