He is now far more marketable

Bale might have been a star for Spurs, but that does not make you a star on the world stage.

Playing for Real Madrid and winning La Decima with them has now made Bale a world wide figure and a very marketable one at that.

United are a huge name on the world stage as well and the shirt sales and merchandise Bale would shift could certainly help make a dent in that hefty transfer fee.