In the name of Allah, the Almighty Creator.
Confidence sure is important. But too much of it is not good. Too much of anything is no good.
Prophet Muhammad (peace be upon him) said,"Do good deeds properly, sincerely and moderately. Always adopt a middle, moderate, regular course; whereby you will reach your target (of paradise)."[Bukhari]
Too much of confidence may turn ones into a total jerk who thinks too highly of themselves (takabbur) and amazed with themselves ('ujub or self-admiration) -- ones who think no one is better than themselves that they like to look down on other people, make fun and downgrade them all they like. They think whatever they do is right and the best of actions that they question and skeptically comment other people's actions and preferences.
Yet, they get angry and offended when people do the same to them.
Throughout my short life, I knew and encountered a number of people like this. It is always tiring to tolerate them. While I do not mind being looked down and made fun of; I, too, have a certain limit of patience in tolerating such people.
Tell me: What it feels like when people can joke with you and make fun about you, yet you cannot do the same to them? Yes, it is irritating.
That is why I pray that Allah expands the limit of my patience. And more importantly, I pray that Allah will never ever put me in the same group with them. For Greatness belongs to Allah alone and I am merely His servant who has no power nor any strength over anything without His Will and Permission.
"O Allah! Please place me with people of Patience."