The desire to have something more is the basic human nature. Everyone is in a rush to get more power, more wealth, in order to have a sense of security and be happy although it is an illusion. There is nothing wrong with the desire to have some more money, more material possession, and more power, but the problems starts when it is acquired through intense and selfish desire to feed the greed.
To maintain a decent lifestyle in this modern age, everyone desire for good cloths, beautiful house, nice car, latest mobile phone, sufficient money for the education of children, and of the like. It is realization of living a decent life that actually becomes the driving force to get moving and put in hard work. Your desire to live well ensures that you give your profession, your best to derive the best out of it.
Money by itself in not evil, it is only the means that should be under scrutiny and if the means to obtain money is not fair, then it becomes the breeding ground for many negative emotions, such as dishonesty, jealousy, lying, anger, and of the likes. In other words, when the desire becomes obsessive and often fulfilled at the cost of others need, then it creates a never ending cycle of greed and makes the person suffer the most.
There is no limit of greed, the more you have, the more you want and no matter how much wealth you have acquired, happiness always remains a distant dream. All the material possession, money, and power are a source of pleasure that enhances the level of happiness provided you are already happy internally. Happiness is a state of mind that is not conditional of desire to have more and more.