I agree that there are fools of all ages. But I think confusing "at first blush X seems obvious to me" with "duh, X is totally obvious, fool" is something that most people get over.

Age may not bring wisdom, but it does mean more experience. In this case, the experience of thinking that something is utterly simple, having your ass handed to you, and being forced to recognize that apparently simple things are often fiendishly subtle.