When trading demo account, traders never face moral discomfort and fear to lose money. As a result, they keep calm and always make rational decisions. On the other hand, while trading live account, most of us are afraid of lossing money, that lead to a lot of mistakes. One of my friends was very profitable on demo account, I can even say that he is talented, but when he tried to trade with real money, he just lost everything, cause he was so afraid by the thoughts that every decision matters, that eventually he couldn't make any right decision. And the same is happening to a lot of traders, that are paralised with their fears and doubts. To avoid this, really succesfull traders need to master not only trading skills and ability to predict markets' behavior, but also their mindset.