Confidence is very important. Confidence comes from knowledge and skills. Without proper knowledge and skills if anyone thinks he has lot of confidence, he can make money, then that's overconfidence. We should not be overconfident. Most of the newbies are overconfident. They focus on profit rather than developing skills.
The over confidence comes from a position of ignorance and complaceny in my opinion. Learn as much as you can with practice you can be confident. Thinking you can go into the markets with a funded account without this at least is just arrogance.
I agreed. Self confidence naturally helps you to become stronger and stronger over time. It comes from knowledge and experience, if you want to trade without fear or hesitation you have to build confidence first. Some newbies jump into trading with a little idea of it or after winning a few trades and in the end, they lose their money. This is overconfidence, people are in this market for a long time and are still learning. First, acquire good knowledge and real experience and then start trading.
One of the other major mistake is over leverage and over confidence. A newbie can blow up after having hundreds of winning trades and but one disaster trade. Also, lot of newbies have tendency to fight with forex market instead of trading the market like smart money do. They have no chance of wining the fight.