There are a lot of studies on the link between happiness and money, and many of them are seemingly in conflict with each other. I think part of the issue is that happiness is very hard to measure. Personally I don't think of money as something that brings me happiness, but more as something that helps me avoid negative emotions like stress or fear. Since the money doesn't directly contribute to my enjoyment, it doesn't really increase my happiness, however my life is significantly happier overall when my financial house is in order.
Here are two articles on studies about money and happiness, both reaching completely different conclusions based on varying methods of measuring the impact of money.