It's a nice attitude to have in a perfect world but what about this one? In many contexts, especially where there is high noise to signal, people will tend to believe/bet on/buy/hire/have sex with the guy who seems so (possibly over-) confident and makes lots of (possibly empty) promises over the guy who is humble and annoyingly realistic. I can't remember which firm but the leader of a cosmetics firm once said "we don't sell lipstick. we sell hope." I think that's true for lots of social interactions. So this attitude is better to have as a hat one can take on or off, depending on the situation. If you're alone or dealing with knowledgable people, yes, wear your humble hat. If you're selling something or yourself, wear the other one. Just to be clear, I don't like it how it is. But at the moment, being intentionally misleading sometimes, even to the point of eating your own BS, is a valid strategy for worldly success if that is what you seek.

EDIT: Just to be clear, what I mean by "intentionally misleading" is more like hyperbole than like lying. Steve Jobs claiming the "best phone in the world" is hyperbole. Bernie Madoff claiming the "smoothest returns in the world" is lying.