You indeed need to know when to stop because when you do not know when to stop it can deliver you a lot of problems in the financial section in your life.
Greediness is also playing a role in this if you are this you can get addicted..
Yap your right, because if you are going to be that too much greedy then for sure that would let you fall into losing or being bankrupt someday.
Because it happened to me, when I was still that greedy every time that I will going to gamble, I wouldn't be satisfied if ever I am going to win $100 for one day.
So instead of stopping, I will going to keep on gambling but that would fall me into losing.