To quote Ender's Game: "I am not a happy man, Ender. Humanity does not ask us to be happy. It merely asks us to be brilliant on its behalf. Survival first, then happiness as we can manage it."
It doesn't really answer why we commit suicide. But it does give an answer to why we aren't happy.
It doesn't really answer why we commit suicide. But it does give an answer to why we aren't happy.