There are lots of rules to be a success trader and greedy plays a vital role.While trading never be greedy. If you become greedy while trading then you can be assured that there is 90% possibility to be a losser.
You are right absolutely, but on the other hand, there are traders who actually don't know when they go from being patient to becoming greedy, this is a subject that I think needs to be critically discussed, there are traders who can mistake being patience for being greedy, while others mistake being greedy for being patient, there is actually a very tin line between this two that most times, it's hard to differentiate.
In other for a trader not to get this confusion, I think it's better to use "setting realistic targets" as a better reference, which means that, when a trader sets a target, and his or her trade hits his target, its better to take the profit, close the trade and move on to the next trade.