It's really quite simple, Spaw. We are so stupid because we are in the grip of the ego. The little, fearful, protesting ego. The thing that identifies itself exclusively with the mind and the body (which are both mortal) and says:

"I am completely alone, separate from all else that I see. I am in danger and need. If there is a God (which I doubt) he is impossibly far off somewhere and must be bargained with and pleased so that he will spare my miserable self from total destruction. And he probably isn't there anyway, so...I must fight and compete with those around me in order to survive. Nature and other people are a constant threat, and I must find a way to control them. I matter, others don't...unless there is something they have that I want!    Then I am willing to suck up to them and be nice until I get it. Love? Love is merely attraction, sexual desire, and need. I love only what I am attracted to and need to keep me satisfied. I don't love those whom I am not attracted to, and they are of absolutely no importance to me, unless they have money or power. Most of all, I fear death! What can I do to avoid it? I know...I'll make a shitload of money! No...wait...that won't work in the long run. Argh! I know...I'll join some crazy religion that promises me eternal salvation even after death...and...and...I'll obey all its stringent rules and regulations and persecute all those damned who don't belong to it. Then maybe (crossing fingers behind back and sweating profusely) I'll be safe at last! And if not...well, he who dies with the most toys wins. That's my credo. When you're dead, you're dead, and who cares anyway after that?"

All of the above is totally wrong, completely fallacious, and plainly destructive, but it's the way the ego thinks.