I don't think it's confidence that makes you naive. I think that too much confidence may keep you from giving up when you should. You believe that no matter how many problems you're facing, you'll find a way to make it work. Inability to take criticism smacks more of arrogance than confidence in my mind, but maybe it's all semantics.

That being said, I agree with the parent. Humility is as important a trait as any, not matter your walk of life.

I tend to think it takes a lot of confidence to give up when you should, too.

You have to be confident enough to believe you'll have another idea next (either better, or easier to execute...).