Seeing that I'm today's world, not everyone is genuinely happy when they see or hear about people winning is enough reason to protect your winnings and sometimes Don't even share because you never can tell exactly who is happy with you and who is going to be that enemy you need to stay far from so they don't get a chance to unleash their hate on the winner such that in some cases it may lead to a very severe case that both the gambler and casino may not be able to contain.
This is the reason why it's very safe and secure to gamble in an online casino: it saves people from the stress of those unpleasant-looking people who don't like to see others win. It's not as if the winning, which you luckily have obstructed anyone from winning, but some people are just naturally haters; they don't like to see the next person excel even when they are openly celebrating with you; their mind is still not totally free.
If you go to some gambling shops here in my local when big win happens before you cashout even when you want to keep it silent some of the shop managers always in one way or the other raise alarm of such winning by doing so they drag unnecessary attention to the player who just win I don't know if it's a way of telling others that big winnings happen here and you too can do it, but it's a very insecure move.