Why? Some people like to spend their free time doing things that aren’t what they do all day at work.

I knew one software developer who basically spent all his free time outside hiking and camping and rarely did anything with a computer when not working. He was a good dev and very competent. Just after being cooped up inside on a computer all week he didn’t want to spend more time on one at home.

It’s not much of a stretch beyond that to simply not owning one.