This is what we call optimism. Just as having both risk-loving and risk-averse people creates a more stable species, so does having optimists and pessimists.

Its a perfectly reasonable thing to believe--just like its opposite--and depends solely on how you're measuring. All in all, I think it depends on the reduce function. If it was reduce(lambda a,b: a+b,[ x.happiness for x in humanity ]), then maybe there is the most happy the world has ever seen. If you took that number and divided it by the population, than maybe the average happy per person has gotten lower. And so on and so on.

I think its definitely possible to believe it.