Although Kylian Mbappé gets the fame, the truth is that other players in the white squad are much more expensive than him.
For example, David Alaba. He spent the previous season without playing. In this one, he doesn't show signs of being at the level required at Real Madrid for a central defender.

But he has an active contract and no one can move him from Real Madrid... unless the president is willing to pay him the remaining year of his contract. And that's not the case.
Florentino Pérez is very fond of him, but he is aware that he is no longer fit to be a starter at Real Madrid.He blocks the path for the young players from the academy and his salary is not what corresponds to a regular substitute. David Alaba has one of the highest contracts in the squad.
Only Mbappé Earns More Than Him
Only Mbappé earns more than him. And he is on par with Vinícius and Modric above Jude Bellingham. Quite a top-level for a substitute.
The best solution is to grant him a free transfer, but the player doesn't accept it. He wants the full remaining year of his contract.
Injuries have plagued him and have prevented him from performing at the expected level. Approaching 33 years old, no one at the club trusts him to do great things anymore.
A Severance of 22.3M
His severance to lighten the salary mass in the squad would cost the club 22.3M euros. Florentino Pérez will try to negotiate an agreement where both parties benefit.
In favor of the Austrian international, it must be said that he arrived at Bernabéu with a free transfer in his pocket after eleven seasons at Bayern Munich. At Real Madrid, he is in his fourth season, and it seems to be his last.
The future has a name and surname in the central defender position: Raúl Asencio. Ancelotti doesn't see Alaba playing as a full-back and wearing himself out while running down the wing.
The die is cast.