Real Madrid wants to use their money properly. When they sign a player, they expect long-term service from him. They don't waste money for short-term good performance. Bellingham is a young player. Real Madrid will certainly benefit if they sign Bellingham now. And I believe he will become an essential player for Madrid now as he gradually matures.
Real Madrid have recently bought Camavinga and Tchouameni for their midfield positions, and they have Valverde there who is young as well.
I feel that they won't be making big money transfers for midfielders any time soon.
Bellingham is a great player though - and half of the top European clubs will be interested for sure.