many times while trading we let our goals down and get greedy or fearsome. the problem are the reason behind, mostly psychological reasons.
two scenarios
a. price went +20% up, we dont sell.
reasons
we dont need the money now
we anticipate more gains (greed, market sentiment)
we see others with more gains (greed, jealousy)
we dream of million (greed, new life vision)
I have often fall for this, sometimes I set a target price, but when it gets there I feel like it's too easy and expect the coin to pump a little bit more but instead a dump happens, it takes alot to stick to your trading plan or price target, we have to be disciplined in other not to be greedy to take profit when the right time come.
b. price went -25% down, we sell.
reasons
we need the money now
we are fearing it will crash more (fear, market sentiment)
we doubt our initial decision to buy (judgement by single point of time)
we see others leaving the investment (fear, mass psychology, group)
we see other investment that are not -25% (fear)
Everyone would feel bad when they see their altcoin not doing well, at this point we have to stop giving into our emotions and try to hold till price recovers.