Sometimes i fell like people hide to gamble is because they don’t want the opinion of others, they really want to do it on their own, sometimes people are very shy and they don’t know how to approach people on advice and discuss some predictions with them, a lot of people act the same way meanwhile some people hide just because of What people may say and they didn’t even want anybody to know that they are gambling
All that you said are correct, but another you missed is they there are some places where gamblers (especially physical gamblers) are always being chased and harrased by the police and other security agencies, and this is because in those places, gamblers are believed to be into drug trade and trafficking.
So, I this type of place, both the good and bad gamblers are always hiding of hidden in a secret place when ever they gather to gamble, they hide themselves away where police won't find them, and passaby won't see them and as well alert the police or any other security agency.
I know this because, it's something that have happened frequently in one area where I once lived on, most gamblers where were drug lord, peddling hard drugs of different sorts and categories, and because of this, both the drug carrying gamblers, and clean/good gamblers were always on the run, hiding from the police and the public when ever they gather to gamble, because if the police see them, they will get harrased, beaten and at most, arrested, and if the public sees them as they gather gambling, they (public) will alert the police, so, this is why some hide while gambling.