Over the years I have seen a lot of the players in most of the major sports don't sit and causal watch other games. They have given a number of reasons.
They have other things to do.
It's their job and they don't enjoy watching others work any more than we would enjoy watching our contemporaries at work.
They are busy watching game film/spending time with their families/taking a break before getting back to work.
They simply don't care.