sure it can but if your profit was already high . higher greed will kick in and in your mind you say that you will play more because you are lucky but what if you loose  ? all your previous winning and effort will go down the drain  .  this is why i would say that greed is bad not only in trading but also on gambling and other stuff's   .  earning sufficient income is already okay because if you can manage it well  it can go along way and it can grow if you save them up