It has always been the "emotion" that has wrecked even the best of traders. Fear of loosing much and the greed of not wanting to take profit when supposed. Many traders have very perfect speculation of what the market is and the possible outcome but they prefer to violate their own rules by compromising when they see perfection has been achieved.
Violating the rules that have been made will certainly have consequences in the end. Those who are driven by emotion, are too greedy and do not have the readiness to tackle every problem when trading. People like that will never reach their peak, they will even tend to regret decisions that are not taken properly. They don't manage properly so trading will only give you losses and no increase whatsoever.