These lines caught my interest because for me I find it really vital. Greed is a very big factor most traders battle with and it is not limited to beginners alone, even experienced traders fall victim of not been able to control their Greed level,  it will also interest you to know that it applies both when you are winning and when you are loosing,  it is not just when you are winning alone that you get greedy,  you can be loosing and Greed will set in and in a bid to recover you chase losses with bigger lots and leverage.

This mostly occurs when the traders lacks proper knowledge of the market or the trader is beginning to loose sit of market psychology and dynamics and allowing emotions to come in probably because they are looking at a target and hoping to make some quick money with which they are going to use to settle a quick bill, this is common with experienced traders,  they can get to a point where they suffer same fate too. As a trader make sure to get as much good knowledge as possible and stay disciplined at a times.