Many reasons, he knew he has tarnished his reputation and abvioulsy wants to reach teh top again. Why take a 'risk' and choose a place with familiarity with lots of your palls. Besides perhaps he wasn't convinced by their project even if the money was good. You can't have Dinho along side Sturrigde, Hamann, etc.
You can't make a case for every player choosing prestige over money but you can quite comfortably say with the modern game, the majority of them would choose money. There are exceptions ofcours, why would Kaka flirt with Prem clubs all the time while at already a big self proclaimed 'family' club??
Benzema could easily choose Man C over Real, but perhaps if they money is equally close and he always dreamt of playing for a 'traditional' big club in a league like Spain, he would easily choose Real, Barca or Man U over Citeh.