Confidence
Let's imagine a graph. There are two axes: difficulty (y-axis) and knowledge (x-axis. Let's also define a line with a positive slope (let's call it the line of comfort). This is a line that represents one's comfort level in an area or field.
Okay, with all of these definitions set up, let's put ourselves in the mindset of people who I call confidence-protectors. Where might they deviate from the line of comfort? Well, they certainly don't want to tackle difficult problems until they garner the ncessary knowledge to solve them. So they take the underhanded route on this graph - going first to the right for gained knowledge and then upwards towards more difficult problems.
On the other hand, we can consider people with the type of unconfined confidence that drives them upwards first towards harder problems. Without the necessary skills to tackle these problems, they're forced to learn on the fly, and pushed to pick up new skills faster than their counterpart. Their confidence will probably be dimished along the way, and obstacles might seem way above their comfort line at the time. But let's consider the upside:
When we choose to tackle problems beyond our reach and beyond our comfort levels, we're letting our confidence carry us to learn skills that are more relevant to the problem at hand, and learn more quickly than our more protective counterparts.
As we continue to push upwards towards more difficult problems, we're developing a long-lasting habit that starts to permanently skew our line of comfort to be steeper and steeper.
[inspired by a post from quora]