Those who sell when they make a small profit are not investors, they are short-term traders. If you want to invest in Bitcoin, you must have such a mentality that my invested money will last for a few years or centuries and I will survive here until the end. Basically, Bitcoin is for those who are patient, not for those who are in a hurry.
Bitcoin investment isn't something that needs to be rushed although there are tons of person who have even gotten the idea of bitcoin through the perception of bitcoin being something thats very easy to make quick funds from which is entirely not the case as with bitcoin investment you will have to sacrifice alot to keep your investment standing strong if not you are gone. But the fact still remains that not everyone is willing to have the mindset of playing the patience.