Thanks for bringing this up. This is the issue we face with Rudiger. He is a good player and he deserves the pay he is demanding. But, there is something we need to understand when it comes to paying players.
A club can destroy its team through a salary increase. Yes, some players contribute more towards the success of the club but that does not make the rest of the players less important.
The dressing room can be disorganized if every world-class player is given his demands. Remember what happened in Manchester United, when Sanchez earns high pay with a little contribution to the team. Manchester United players started murmuring about him and some players showed less commitment then.
In general, clubs are very careful when it comes to players salary upgrade