Understanding our personal self would be an advantage to us since we can do things that would always profit us to earn more. Once we understand ourselves as a gambler, there are some certain decisions that we don't have to neglect because they could help us become a better gambler. Ego have destroyed man to people due to there over confidence that they are going to make so much money in a particular bet. Once we understand what to do and how to do it, it would strengthen us to achieve more when we bet because we can always make profits when things falls to our fall when have gain superb experience.
This has a valid point.
One must know himself first before doing anything that could be life changing. It's not that you doubt yourself, but you don't want to end up losing everything at once because you don't know yourself enough especially in terms of making decisions. In gambling, you should be rational. You shouldn't let your emotions get into your way because that will just only be a nuisance. You should know your characteristics, whether it is suitable for you to be a responsible gambler, and you should know your strengths and weaknesses so you could plan ahead with a goal in mind as well as limitations.
Too much confidence can be harmful because you might overestimate your capability than what you could actually do. And being too afraid could hinder you into achieving things. So just do things in moderation.