It takes more to be intelligent than optimistic, yes, but can anyone feel truly optimistic? Maybe they hope for the best, maybe they believe things will become better, but happiness is not that easy to achieve. Do you believe that things will become better or that things are as good as they can be if you're an optimist? And does that mean you're instantly happy? You can't just say "I'm happy" and suddenly be rainbows and sunshine. Yes, you've succeeded in the real world if you're intelligent and in a high position, but have you succeeded in your own life? I would hope that if I were intelligent and miserable, I would eventually find a way to dig myself out of my own hole. But anyhow, just because someone is dumb doesn't mean they can't succeed in life. Unwavering happiness is rare to find in any crowd. At the end, I think I would rather be blissfully happy than a miserable genius. I guess we seek more knowledge because we know we don't know everything. Maybe an idiot won't actually make an impact on this world, or come up with a life-changing idea, but they'll probably make a change anyways, regardless of whether they're aware of it or not. I would rather end up dying, knowing that I lived happily, even if others never thought much of me, than to live a sad life even though I've done so much. There's a reason why people wish to return to their childhood, the days of ignorance and lightheartedness. I can understand why people chose the other one, but I think it depends on what matters to you most.