It´s not, there is no way to tell players that you have the lowest wage budget in the league and they are welcome to request a transfer, you wish to keep them but the finances simply do not allow for higher wages. It´s nothing against the players themselves, if they are good enough they should get a contract elsewhere.
The problem is that in FM you can rise through the leagues quickly and players don´t access their own "worth". It means that you can have a 2 star player demanding ridiculous wages because they find themselves in an "upper league", they request a transfer or get unhappy and that situation about "own worth" is only resolved when they get to a new club, often at much lower wages.
I kept a central defender at Wrexham because he is influential, he is not demanding first team football but does get to play more often than he really should, he is just not under any circumstances championship material. He just requested 15k and I have to let him go, he is already earning far more than he will at any other club along with 3 other players.
One example of wage weirdness and FM is full of them :
Charlie Goode is in my championship squad where he demanded 22k a week to sign a new contract, in real life he is at Brentford playing for 8k a week. He is a good Championship player but another I have to let go, I simply can´t tell him that the club doesn´t have that kind of money.