I still prefer not to talk about my major gambling profits because people will ruin it and easily make you lose it. I like to be cool and just tell a few people that they're so close to me that if they know later, they won't get upset. This is because people around you can have different reactions. For example, if you make a lot of money out of something they might be trying to steal it or change their opinion about you.
When it comes to money then no one should be trusted even if if they are very close to you because people will look for benefits from your gambling rewards and sometimes it will be hard to resist ourselves from letting know the people about our rewards but its better if you try to be cool as you said.
Yes, we need to selective to choose the person that we want to tell about our winning so they can keep the secret of our winning. We don't have to say to all people that we know because we don't know what they think about the winning that we can get. It is normal if after they know about our winning, they want us to buy some food or celebrating the winning moment with them but we don't have to tell how much money we can get.