At some point in our lives we will make mistakes. These mistakes can happen for a number for reasons, whether it is because we have made a bad decision, or we are overconfident. Most of the time it can be because we are overconfident.
Research on human judgment and decision-making has shown that people have a tendency to be overconfident: they attach more confidence to their judgments than they should. .
An example of someone being overconfident is someone is at a casino and they have had a winning streak for the past five games of roulette. They being to feel confident that if they place all of their winnings on that "certain number" that is uncommon for the ball to land on, that they will win because they have had such good luck so far. Once they place all of their winnings on that number and they do not win, they have just lost all of the money they have just won, and are now left with nothing. .
It seems now that having confidence in anything is bad; this is not the case however. If you have confidence in yourself, you are able to achieve the goals you set for yourself in life, or whatever you may want to achieve. On the other hand it is not good to be overconfident. When you are over confident about yourself you cannot the picture clearly and can make some very poor judgments. People can become to trust worthy or fixated on what they want to achieve they think what they want to happen will definatly happen for them. .
In the case of Macbeth he becomes very confident in the fact that Birnam wood will not march upon Dunsinane and that no man born of woman will be able to harm him. He is very confident in these two things because it is impossible for the trees of Birnam wood to grown legs and feet and march. He is also confident that all man born of woman cannot harm him because all men are born of woman. He does not put any more thought into these prophecies to see the real meaning behind them.