Trading on a demo account and on a real account is different. When you play on a demo account, you are luckier, and when you replenish a real account, you get more loss:(
that is the kind of effect that emotions have. when you are demo-trading or for example if you are trading on paper or in a spreadsheet you are just playing around with numbers so you sit there and think and make a move.
but in reality, specially when you have a significant amount of money involved, you can not think straight in many situations for example when all of a sudden price of what you have bought drops -10% and continues down.