I think that gambling advertising on social media is ineffective and very expensive, since gambling is basically prohibited in most social media
Which of the social media forbids gambling adverts, i think nost of the social media platforms allow for adverts of any kind and these gambling platforms also have their own social media handles they use in making advertisement on their services, they also make use of social media influencers, paid ads services, bloggers, and uses other social media platforms to make adverts and pay them while some are done for free, just as you can discover this forum the way we have a number of gambling platforms making their awareness on this forum through a signatory campaign.
This kind of promotions are not prohibited in my country as many are still advertising a specific platform and you can still see a sponsored post which relates to gambling this is also why many are exposed already into gambling and even the young ones. Social media campaign for the gambling sites seems very effective, you can also add the vlogger who are part of the promotional campaign, there’s so many ways to market the casinos nowadays.