For a gambler to be able to control his emotions, he must use the amount of money that he van afford to lose. That will make him let go of his losses. Also, he must not be greedy, because some gamblers after losing little amount, they will love to double their next bet to recover their losses with an additional profit. Only gamble for fun, and see your money as what you are using to pay for entertainment.
The kind of aggressiveness when you suffer from a defeat, a gambler mostly thinks that by adding money to their bankroll gives them chance to recover whatever they've loss during their first encounter, without having that good control over your emotions you'll be suffering for more loses to take place, it's always been advise that use only the amount that you are willing to let go and not gamble the amount that's suppsedly allocated to other important things, it leads you to lose more when you are trying to recover back the amount that you are unwilling to let go.