I think the common cliche, "money doesn't buy happiness" is very complicated. On one hand, grumpy/miserable people will likely still be that way regardless of their economic situation. I don't think you exactly change as a person because you accumulate more money.
The big thing to me about money is it gives you independence and security that's not to say, you'll be happy, just have less worries -- doesn't guarantee good health by any measure. However, you aren't going to be able to take that European vacation, buy that fancy car, or go out for gourmet meals on a regular basis without accumulating a substantial amount of money. And these types of things can improve your quality of life.
So yes in many ways, money can "buy" happiness.