the testimony was raised by rollbit, not the player who managed to get the win, and it seems that the players who use big money to play so that they can achieve big wins, not many will show their victory because it could be risky for him and usually the one who shows it off is the player who wants get followers.
But if I'm not mistaken, has anyone ever won bigger than that on rollbit
Some players want to share their big wins while some want to remain silent but as you are aware about the username only your position is not at risk completely and you can do it.But still it's our own preferences and casino needs it as advertising promotion to attract new players.If talking about big wins then yes there must be similar big wins before also on Rollbit like the NFT lootboxes giving away million dollars BAYC and punks.
I agree that it's not really a smart way to publicly share what you win yourself, if you block the names out then it's fine, but telling who you are would be risky. Unfortunately, I do not have that risk, since I never had that much money in my entire life, let alone wager it or win something.
But, people who are rich would be bothered, there would be people trying to login, try to hack, try to bother them with pm's and phishing links and many other things. That's why it's not a smart idea to share who you are when you are a rich person. I hope to god that I would have that type of problem one day

. I rather be rich and scared then poor and relax

.
It always depends on people perspective towards this since there are people who would like to be anonymous and don't want to share their winnings, also their are people who want to flex their earnings for marketing purposes or other to boast then want other people to drool on the amount they win. That's why this discussion depends always on what people prefer because not everyone has the same likes about showing or hiding their identity after those huge wins they encounter.