Why do you think humans destroy themselves?

Why do you think humans just sit back and allow everything that slowly destroys us to happen? We are allowing the world to become over populated and the consiquences of that will soon show. We pollute so much and detory our ozone which is there to protect us. We still fill the skys with CO2 causing a more rapid global warming. Why don't we do anything to save ourselves? I do all I can but one person out of 4 billion is nothing.