I think many casino platforms are promoting with a targeted audience setting to bring in new users, besides the gambling community in the Facebook group is very large so we have to be actively involved to interact in active gambling groups, but the problem may not be crypto-based gamblers.
Gambling has become huge actually in social media.
In fact, I've got a lot of friends in real life and friends only on social media that have been posting gambling-related stuff. Most of them were all about their bets.
Starting with social media is a great idea and the budget isn't going to be that much but you need to be consistently advertising there for you to cope up with target audience and customers.