Some people who keep their gambling a secret, in my opinion, are people who don't want to take risks, because I myself do it like that, I don't want anything that could trigger conflict with the gambling I do. Therefore, keeping the gambling you do a secret, including the winnings you get, is good.
Keeping your gambling habit equals not wanting to take risks? Not necessarily so. People who keep their gambling habits a secrets perhaps don’t want their affairs out and about in the public. Risks has nothing to do with keeping your affairs private as you could always and at anytime, take same huge risks privately as others publicly do without anyone knowing about it.
I’m a big fan of keeping your affairs private, only sharing to those friends and family close enough and who deserve to have certain information about your activities.
Whatever we do publicly or privately has its advantages and disadvantages. Gambling is a game that has been privatized due to the recent integration of online casinos. So, people won't know if we gamble unless we open up to them. And nobody goes out on the street screaming that he's a gambler. As you said, Iroh, players only tell people they think should know, close friends or family. Sometimes the winning could be so outrageous that the player will unknowingly tell many people, out of joy, that he won big in gambling. There are cases like this where people wouldn't mind unveiling their gambling attitude. It has some advantages, especially in times of difficulty or problem gambling.
Those who kept their gambling habit a secret from everyone would have a hard time telling people when they've got an underlying problem. Talking to people as suggested is fine, as they'll serve as a watchdog on our behavioral change. This doesn't mean the whole society should know about this, we all deserve some privacy. Keeping such thing as gambling a secret, makes it sound like gambling is banned in the country. In a society where gambling is accepted, gambling platforms are built in all corners of the street. What is there to hide or keep a secret? It wouldn't hurt the people around us if we told them about the attitude. I don't see anything wrong with sharing the information. It shouldn't be a secret.
Found some good points that I support in your post. It isnt necessary to yell on the street "I am a gambler! I am a gambler!" But it also isnt necessary to cross the street or try to ignore the question "Do you gamble?" when somebody asks. I am not keeping in secret that I gamble. And I dont welcome people "Hello, my name is TopTort777 and I gamble". And you know what, I have never had any trouble or any kind of harassment from not hiding that I gamble. I see only disadvantages of hiding such hobby and see no advantages.
Btw, would gladly listen to any advantages of hiding gambling hobby. (opinion from those where gambling is illegal does not count).