Why are Japanese very happy people?

This is something that I have observed for a while. I know that they are rich, but Americans are rich too. Is it because of the fact that they have an ethnically and linguistically homogeneous population in combination with one of the highest life expectancies in the world?

Cultural diversity has it's obvious drawbacks (nigs) but it makes things a lot more interesting. American aesthetics are far superior to everything else in the world, we have our share of tards who go off on a tangent and end up like guidos and rednecks or whatever but in America there is nothing to stop someone pointing out that they are stupid fucking faggots, in this environment of criticism those who are intelligent and talented enough refine their art and develop sophisticated personalities far superior to those living in more stagnant societies.