Having greed is good, its the stupid mistakes that make you lose money. Greed is wanting more money, holding more than you should is not "greed", its a mistake, if you know what you are doing then you would sell at the top and buy at the bottom and make more money aka be greedy.

So all in all, do not make all the mistakes confused with each other, because emotions in trading world is very dangerous and mistaking which emotion is which could be even worse and that's an important thing.