Compulsive gamblers will not tell you how much money they've lost, they only want to brag their winnings, this is to justify that they are doing ok and good in gambling, even if they are losing everything to gambling, if you cannot control the time and money you spent in gambling you are going to lose everything.
Every human tries to make themselves look good in front of others because of fear of questioning and being judged. This is more in those who have not yet got a proper job and are trying their money in luck based games like gambling. They are obviously broken inside and they know it, yet they have to act haughty and that they are doing well to cover up their misdeeds.
Leaving gambling habits to become a compulsion is what should be prevented. It is possible if one is determined to stop playing. But starting it is the most important step.