After seeing that you could have bought a new motorbike or buy an expensive watch on all your losses that you have computed.
Before I gamble, I already knew that gambling is addictive and most of the people ruined their lives because of this. But I still tried it and experienced it so that to know if it really can ruined people's lives. It is true that gambling will just give us headache and stress if we're not lucky in a certain day and it is very difficult to retrieve the losses that you had. Gambling is not a source of profit, it is not that easy to manipulate money when you're in that situation. Recording and making a gambling history will help you monitor the range of your losses and the maximum money you've spent playing and then suddenly you will realize that gambling just brought you disappointments.