We dont know what he's been offered in cash terms.
Look at it this way: every player we have always says how Coleman is crucial to their well-being at the club and team cohesion. There's coaches employed by Everton who do a less important job...
I cant imagine the offer to be on anything other than massively reduced terms.
I can see the sense in keeping him on as a figurehead who can integrate new players into the set up and make the bench as a back up RB.
I'm far more bothered about us getting better than I am about them. If 'giving' them £30m makes us better then who cares if it also helps them, it's a proper weird mentality to think differently to be honest.