Why do guys with really hairy arms/backs wear sleeveless shirts?

I know this question is really random, but I was wondering about this today. I work in retail and there are so many times where guys with extremely hairy arms and backs come in with sleeveless shirts for all the world to see. It's not even like it is just a little hair, no, it is a huge amount of hair that mimics fur. I know that this look doesn't look good, other people know this doesn't look good, but do these guys realize how bad it looks? Why do guys insist on going around like this? Do they not realize they are that hairy? Are they afraid to wax or shave? Any insight would be helpful!