This is common in every gambler their greed towards money is high because they are not contented on their winnings. They continue playing even they know the risk of losing is very big. We or they should be happy with the winnings no matter how big or small is that. This can be prevented if we know when to stop and have a good self control on not betting again after gaining some wins.
I believe everyone here have seen something like that , and guess if it was bad and terrible enough?
I think it was , that kind situation for me considered as the worst mistake