It doesn't work like this. Even Casemiro has only been a mainstay in RM's midfield for 7 years and there's talks of phasing him out gradually.
Very rarely do players last at clubs like RM for a decade.
This is where you take the gamble. Right now with the Mbappe money they saved, Madrid have the room to take this risk.
100 million is no longer that mad.
Madrid recently spent 100 m plus on one of the best players in the world, an attacker- Eden Hazard. People thought he was a guarantee to perform but look how it turned out.
Tchou.... is one of the biggest midfield talents in the world.
From now on, this is how it'll work. If you want a superb young star with massive potential you have to fork out atleast 80 M.
Monaco's initial asking price was 80 M apparently. Real agreed to pay a bit more because clubs like Liverpool and Paris were massively important and Madrid wanted to avoid a hijack at all costs.
They got Rudiger for free plus have massive transfer budget.
If he gives Madrid a solid 5-6 years winning League Titles and 1 or 2 CL as a starter, it'll be fine.
Neymar transfer has fucked up the market and Oil Clubs will always make you pay a shitload for this kinda player.
For RM currently, I'd call this a calculated risk and a pretty great signing. Wish we signed him.