Saying it's totally impossible to achieve those winnings sounds so harsh to me, as there are winnings that can still be achieved in a casino, but they can't just happen in every game they place, which is where the doubt comes in because it will be very stupid to believe that all those winnings are true; some are, but most of them are likely to be manipulated.
Indeed, there are certainly people who can win at gambling, whether by using small or large capital, also with small or large bets. However, if you compare the wins and losses that occur in someone who gambles, then losing is something that happens more often, even with me and including you, who in my opinion experience more losses than wins, the rarity of winning is common because basically the chances of winning for players are smaller than the chances of losing.
The number of streamers who can get big wins, I myself think that their wins are manipulated or have been arranged, because of the cooperation between the casino and the streamer which allows the goal to tempt many people to gamble, especially those who are still new to gambling who are likely to be interested.