It is easy to say these things than practice them. It is not everybody that has the emotion ability to see there investment going down in value then do nothing about it, most people would want to cut their losses. That's why I tell people to always take profit and move on before the market turn on them.
Very true. the purpose of investing is to get profit, sometimes people will wait and serve their greed, and of course that is very bad, especially in investing in crypto with very high fluctuations. selling is not a wrong thing to get a profit, so prioritize profit first