Competition among online casinos is becoming really tough. You'll only last in this industry as an online casino if you have a lot of capital and are truly willing to promote, like what big online casinos like stake.com and BC.Game are doing.
You can see their ads everywhere, whether in sports events, crypto explorers (like Etherscan) and social media influences/ambassador. And like you said, they hire or sign contracts with streamers. But for sure, even these small contests here in bitcointalk can somehow help their marketing. And there could still be profit if many have joined.
Advertisement and promotions requires a lot of money while not all casino is able to spend that much money but there is always a way to lure players with lower promotions budget.
Of course it should be unique, it should be attractive, and it is not an easy task to do obviously
Creativity from the marketing team is needed to make a way of spending less budget but effective to attract players.
By the way, OP is not online for almost a week now, hopefully he will come back soon because I always think that the casino is giving up when I see a rep of new casino is not active after they stopped promotion and advertisement in this forum.