It depends on the situation because most of the cases the chances of losing is high and people think they are gambling expert it will lead them to invest higher amounts in gambling. So don't consider you are gambling expert if you think so then you will start losing more money.
True. Overconfidence can result in big problems. One of my friends started to play small games in beginning. When he started winning, he used to play multiple games at the same time, saying that he can manage all at once. Then he started even watching movies while playing these games.
And the result was obvious, he started loosing a lot as he was not able to give attention to individual games.
That is what is called greed in gambling and cannot control emotions well. If there is someone who has won most of gambling and then does not stop it, then in the end he will lose too and will continue to gamble until he wishes to take back his lost money and then he will become a gambling addict.