You do not need to be greedy, especially on the crypto currencies market while falling. The market is very young and when it falls, you should be happy even with a small percentage of your profit. I am going out of any coin when I have 30-40 percent profit.
Its easy not to be greed but usually, uncontrolled emotion always happen when you are earning profit.
The amount of rewards that you can get will just part of you plan, and if you decide to be more greedy then its a higher risk, and it can lose your money. Greediness should be on the right timing as well, because when everyone is afraid to invest then you have to be greedy on that part.