It's not really a bad idea talking about your gains. What makes it bad is the way how a person tells it to other. You can tell it in a nicer way, it's not bad to feel happy and excited telling it to others. That's just our initial reaction. It's also not bad to use it to inspire others. What's bad is bragging your win. Sharing and bragging is different. When sharing, you'll likely to just tell it to your closest friends. While in bragging, you're telling it to other people that is not necessary for them to know about your wins.
I think it's still a bad way to share it in a "nicer" way, Imagine you win a big amount of money and you share it to your friends and then, the next day you lose it all because, you bet big and try to multiply your money, What are those people are gonna think of you? When it regards to gambling it's good if you just keep it to yourself, winning or losing keep it private.
If you win big in a traditional casino then it is very likely that you will be the target of robbery among the crowd that is why you should be wise and smart in handling your winnings or else you bring home nothing. On the other hand, if you win in an online casino then you will still be a target of robbery by hackers once you brag about your winnings. For me, if I win big I would rather keep it as private as possible to safeguard it and also I think people will think i’m bragging that I won so it’s better to keep it to myself and act natural as possible.
Exactly, Winning or losing just keep it to yourself, same with your money if you have a job, you don't need to prove yourself to other people. And besides, it can harm you if you share it to wrong people or posted it online LOL, just enjoy your winning by yourself.