The human race lived for many many years before the invention of money, and I'd bet many of them were happy. Money and the whole idea of ownership and possession complicates everything and adds more stress to what would be a pretty simple life. We're all brainwashed to believe that we need certain things, when we really don't. And we're all brainwashed even further to the point where we believe that in order to get the things necessary for us to survive we need to work at some job so that we can get money and buy them. It's simply not true. It's possible to live without all these things. Admitedly, probably 95% of us, myself included, aren't capable of such a life for pure sake of not having the knowledge of how to survive off the land, but it's possible.

Also, I think that we as humans would have a better sense of community if this were the case. If we were forced to live off the land, we would find that we would need to depend on one another in order to survive. In this society everyone is so isolated and distant from one another and "independent" that we don't realize how much we truly depend on other people that we never even meet. Someone's hard work and sweat was poured into every food item you buy at the grocery store, but no one ever stops to think about things like that. We just go buy our milk and bread and feel proud that we're doing everything on our own, which is nothing more than an illusion.

My definition of happiness:
“What is happiness? The feeling that power increases - that resistance is being overcome” -Nietzsche

But in today's world everyone wants a life free of struggle, which completely misses the point. Struggle is needed for happiness. In order to be happy you must overcome some great obstacle. This helps you to figure out your strengths and weaknesses and allows you the opportunity to fulfill your potential and discover what great things you are actually capable of.