People that do not have money think that money is all they need to be happy. People who have it are not motivated by it. It is only one factor out of many.
Dzeko was named "first choice" only as a psychological ploy to give the appearance that he was given a chance. I think Pellegrini just said that so that he could justify dropping him later after a poor performance or two, which every striker is bound to have. Even after a stellar performance against Newcastle in the first match, Pellegrini refused to say that Dzeko played a great game because he did not score. Next game he scored against Cardiff, then he was replaced by Negredo in the following match after only playing 45 minutes.
He pretty much replaced him with Negredo at halftime who scored the winner in the second half. So Dzeko gets replaced after one half of a bad performance, and becomes the third choice striker almost overnight. That tells me that Pellegrini was never serious about building the attack around him in the first place. You do not replace your first choice striker just because he has one or two bad performances. Now you can rgue that Negredo forms a better partnership with Aguero, but let's not kid ourselves that Negredo wasn't always meant to be the second striker. Pellegrini was just playing mind games and I think he fully intends to sell Dzeko in January or during the summer transfer window.