Most NFL referees have other jobs and work those during the off season. Some NFL referees are business owners or attorneys.
NFL referees throw their hats because they have already thrown their flags and the play has not stopped yet.
NFL referees were never volunteers. However, many of them got their start in recreational leagues near their hometowns as volunteers.
because you are mean
The referees in an NFL game have a very difficult job in calling the game they are assigned to. The highest paid among the referees is unknown.