I won 0.175 BTC once in a poker tournament, more than 2 years ago, and I think there's no one left among the people I know, who didn't hear this story from me at least once. 
But hardly it was an amount sufficient to put one in danger if he/she talked about winning it (around $400 at the time of winning). Of course I agree with the OP on that if someone can't stop bragging about winning really big, you are putting your life and the lives of your close ones in danger. Winning big money should be enough to satisfy your ego. Don't be greedy for another satisfaction in the form of admiration by the people you know.
But hardly it was an amount sufficient to put one in danger if he/she talked about winning it (around $400 at the time of winning). Of course I agree with the OP on that if someone can't stop bragging about winning really big, you are putting your life and the lives of your close ones in danger. Winning big money should be enough to satisfy your ego. Don't be greedy for another satisfaction in the form of admiration by the people you know.you won it offline or offline ? the amount was decent but not that huge for such a tournament . btc price before were also cheap ( before 2017 bull run ) . small or huge amount , you wouldnt know if whats running in the mind of the people that listen's to you when you share this story . desperate people can do harm to others not just by greed or wanting to have that money but also if he is jelous enough . we still need to keep private when it comes to winning and money matters .
For $400, I don't think that would put your life in danger unless you are living in a country where poverty poverty rate is high and that amount is so huge.
That amount in my country can be earn through their salary so even if you brag that amount, you'll not get harm.
Maybe around $10,000 or more, that would already put your life in danger.