Facebook is too restrictive regards crypto content that they have become an unreliable platform to advertise. Instagram is more picture related platform and Tik-Tok video related, and although I'm not familiar with their policies, I think it's pretty possible to advertise gambling content there when adapting the ads to each platform style. On Instagram banners explaining promos could be displayed in abundance and at Tik-Tok short promotional videos could be made. About Bitcointalk specifically, it's more gambling oriented advertisement, because it's a crypto niche which also embraces a significant portion of gamblers' community. So we could say the traffic here is more valuable than the traffic at social medias and that might be the reason why casinos invest so much time and money at the forum.
I think twitter is more wider in adaptivity, when it comes to hashtags and sharing images and videos. The best thing being a photogrpaher I discovered was NFT photographers community, but very bold images which insta would ban due to policy are there on twitter. I think they can try twitter as well.
Yes, twitter is an useful tool for casinos to advertise their promotions, giveaways and special offers and it is really popular among adult users from 25 to 34 years old (38.5%), which fit the target public of casinos. But unfortunatelly, when ranking every social medias of the internet, twitter hits only the 15º position, in number of accounts. Most people are interested in short-videos content these days and casinos need to adapt their marketing to this reality in order to attract attention to their services with maximum efficiency. Even youtube had to adapt themselves to this by creating the "shorts" feature.