That’s a really real take, emotions in gambling can swing fast and hard and not everyone knows how to manage that and I think keeping things secret like you do is sensible. It helps you stay grounded and avoid needless pressure from others, Personally I strive to stay neutral too whether I win or lose also I don’t like the idea of rejoicing too loud or pouting too much. At the end of the day it’s your money and your mental serenity that matters most.
Your mental state should be what you put first; whatever will lead to stressing it or bringing external pressure to it should be avoided, which announcing your winning or losing will definitely contribute to. As long as you don't stay silent about your gambling involvement, those who are close to you will also not be quiet; they will always want to put you into discussions, which most times will make you uncomfortable, and yet you can't do anything about it because you started it in the first place.