I am enthralled by your precise and vivid descriptions of the way humans cause themselves harm by acting recklessly and unabashed. Personally, it is my strong belief that humans feel the need to over-compensate and such because they have a rabid necessity to think of themselves in the highest manner possible.
Even those who claim to be a "good" person can in fact be an overly selfish or even fraudulent persona. I will not launch into my rant on "good and evil" here, however. It is the natural human desire to feel superior, such as if a man has done a good deed, whether it be from the heart or out of a need to feel appreciated, he then justifies conducting himself with a inwardly condescending attitude with someone with a seemingly lower moral code. That, in itself, is a source of great irony. (This is not the case for bullies, however) Sometimes, people have been known to take it too far, just to keep themselves content.
As you mentioned, with the bear example, a weaker, unarmed man may flail about wildly in feeble attempts to combat the bear, all out of the need to feel strong and empowered. It can be safely assumed that if that man, who somehow managed to rid himself of that pressing dilemma, would boast his experience, only making himself look better. We, as humans, have an inbred need to feel superior, which is what I believe the cause of self-destructive psuedo-toughness to be.