As an ideal, I have little doubt that most people believe this, it's just that it's something that's very easy to exploit, and you stand to gain a massive amount if you do. Its a real tragedy of the commons scenerio. With millions and billions of people and just one commons, there's plenty of tragedy to go around.

It's still worth it to try - I find it difficult to give up completely. Most people I meet are not evil, and it's not like you're going to make it out alive at the end regardless.