In order to be worth that kind of money at that position you have to be at minimum a fringey Hall of Fame type talent. Roquan Smith might actually be that, but he hasn't been so far. He's been very good, but not great.
He has held out once and held in a second time. Whatever the Bears sign him to would almost certainly invite another situation like this two or three years down the road (should he play up to the value of the contract). It's just not worth it. Not for the on-field stuff, not for the leadership, not in the big picture cap outlook.
Just to put this in practical terms. If Jaylon Johnson breaks out in a big way this money can go straight to him. A younger player at a premium position. Its a no-brainer when you think of it in those terms.