i have no idea about average napoli fans' salaries, but the fact that their average attendance cannot constantly reach beyond 40k is pretty sad indeed. if napoli were an epl team they would probably fill any 60k stadium with the teams they usually have.
it just confirms that first of all, italian football needs some new stadiums. shitty san paolo is not an attractive venue indeed, and a good team won't be enough for any club to attract the fans.