Once the activation energy can be maintained (basic skill and consistency) the learning curve is the steepest at the beginning of any given field; the setbacks

Once the activation energy can be maintained (basic skill and consistency) the learning curve is the steepest at the beginning of any given field; the setbacks are still rare and surmountable (and just mostly add to the confidence). But the human mind is only able to suffer a finite amount of beating and at one point your perceived competence level will collapse dramatically, overcorrecting in the opposite direction. However, the reward structure of overconfidence can be used to maintain the momentum and once you hit the hard wall of insurmountable incompetence congratulate yourself that you actually walked the path of knowing practically nothing. It's the hardest thing to fully admit one's own ignorance and easy to see all around you, it's only when the giant rationalization machine buzzing inside is finally fully exhausted; for a brief moment the crushing vastness of the unknown pours in. So in a way overconfidence is just unused fuel. Use it wisely.