I've been thinking about this question all day today. Most of my very good friends (yeah, like I have so many ...) are readers, maybe not the same kinds of things, but they do read on a pretty regular basis. I can think of one or two who don't read much at all, but to be honest, they don't seem to pay attention to much of anything ...
My sisters were never as into reading as I was. As far as I know, they are now pretty regular readers, though I have no real idea how many books they may read in a year. I do remember that when my middle sister was in high school, and had to read for a literature class, that she would set the timer each evening for one hour. As soon as it rang, she stopped reading - even if there was just another page left in the chapter! This used to really amaze/dismay my parents. Now she reads things she wants to read, so I'm pretty sure the timer gets used for other things ...
A lot of the people I know who don't read much were actually turned off completely by it in high school or college, it seems. I will admit that if I hadn't been an obsessive reader when I encountered Paradise Lost, by John Milton, in high school, I may never have voluntarily picked up another book. (I got in a lot of trouble in class, when the teacher asked me what I thought about it, and I said it made me think that Milton deserved to go blind for writing something that boring and annoying. [I'll pause here while many of you gasp in horror.])
My late mother-in-law had a friend for a few years, Dick (or, as I used to refer to him, The World's Most Appropriately Named Man), who always used to be amazed that she liked to read. He would always brag that he "hadn't read a book since he finished high school." It showed.
I know a lot of people who say they read at work all day, so they are not interested in reading for leisure. I just figure they weren't big readers in the first place.