If they end up losing him for free, then they will regret that, he is at least a 70-80 million euro player if not more, and losing him would cause them to miss out on that much money, or a player that they could keep and provide a ton of goals and assists every year. Pay him whatever he wants, only because he can't be replaced, you can pay less for another player and will not get the same results as he could provide for you.
I really think that is very clever from the player because he is really familiar with this League. If he tries to play in the English Premier League or any other league where the football is really fast-paced, he might face a lot of injuries and that is certainly not ideal for the player.
And if he moves to other leagues, he might need a lot more time to get used to but in his new team, I think he will need a lot less time. So I actually think it is not a bad decision from the player. And if he only wants to keep the fans happy I think he should stop playing football and go join the circus.