There is lots of healthy thinking in this thread. Some of the strong themes are to count your blessings instead of worrying about what you don't have, and that money alone rarely makes people happy. Happiness takes something more. And along Maslow's lines, if you are too poor and have no basic needs met, like starvation and constant threats, it would be very difficult to be happy.
I don't think anyone has touched upon cultural influences though. In my freshman psychology class, our professor told a story about two women in their early 20's who had to care for a sick parent. One was very happy, the other very unhappy. The happy one was Chinese and fulfilling her role in the family. The other was an American being denied pursuit of her own goals. Neither is right or wrong, but are examples of how cultural influences can have an impact on happiness.
Back to the "money can't buy happiness" theme, if we define ourselves by acquisition of things, then we lose it all ... It's simple for me nowadays: the older I get, the more I find happiness in my family and friends. These relationships are what truly make me happy. And I play guitar for family and friends !