It's absolutely the base marketing strategy for all casinos and you can check out that every casino shares some big wins on regular intervals on their Twitter handle as they have 30-40k followers over there and even if 1-2% joined the casino after such wins they are in profits.So they adopt various methods to showcase these sort of wins and try to attract more players to the casino.
It is not even about getting new players. I mean, sure, if you get new players that is also great but when you are showing these big wins to your already there customers? That is going to get them more hopeful and they are going to wager a lot more with the hopes of winning a lot. They have just seen that it is possible, so why shouldn't they be excited about the potential of something like that? This is why I believe that we should not be really so shocked for casinos sharing these wins.
It is great to get your customers to gamble even more, and it is also great for others to see how people win big amounts in your casino and join in at the same time, it is a win-win situation.