At first, it sounds like an oxymoron. Although stone and wooden idols are one form of idolatry, a person does not need to bow down before them to be an idolater.
Idolatry ultimately boils down to using one's belief system to live for self.
Greed is far more than just wanting money. When someone believes that created things are capable of taking care of life, greed becomes the driving value for that person's behavior. Greed is far more than just wanting money. There are many forms of greed. It is the drive to acquire more in order to be secure or to become somebody.