I have a little different opinion about it. Yes, I understand that disclosing such big winnings can be a security threat for gamblers as now everyone would know that this person has a big bank balance. However, do you know that every day we hear people losing money in gambling? These are the few news which show how people become millionaires by spending little on gambling and it really motivates people like me who are yet to win any jackpot.
Think that a person spends only a dollar and win something like 50,000$, incredible? We don't see such a return elsewhere except gambling.
One need to understand, gambling is the way in which it is possible to turn a dollar into million. It is also the way in which one can start with spending $1 and end up losing millions. When we talk about the big wins, it is also good to think of the loss that could happen out of gambling. Thinking of jackpot and getting motivated through these kind of wins is good, but we should know our limits on trying our luck.