I feel like paying over 50 million euro for a player who is 30 years old and will be 33 when he ends his contract isn't really a feasible idea.
30 years old to 33yo is usually the age range where football players reach their peak of their career. Let's look at some "30yo or more" football players that are active right now and could very well be in the starting XI of any top team:
Vardy (33, Leicester), Vidal (32, Barcelona), Hummels (31, Dortmund), Kroos (30, Real Madrid), Pique (33, Barcelona), Aguero (31, Man City), Bonucci (33, Juventus), Auba (30, Arsenal), Di María (32, PSG), etc, etc.
50M for one of the best free-kick takers in the world, a midfielder with tons of experience, great passing and vision and tremendous quick thinking on the pitch is a fair price, IMO.