Sometimes waiting is profitable but if you know the fact and this is not consider as greed but on other hand when you know that price will not increase more than this then selling for getting profit is will be suited well.
Greediness in trading is when you have reached your target but refused to exit the trade and it's not because you saw more potential upside movement from the market but you're just greedy and wants to make more money from the market. We should always be satisfied with the profits we have and take profit first then if you see an upside movement, you can reenter the market. Greediness is the reason many individual has lost so much money to the market.
Greediness makes you to go against trading with caution, and when you don't trade with caution you're putting yourself at risk of losing to the market. As a trader you should always put in precautions measures so you don't lose to the market as that can be very frustrating.