It takes time to build a good reputation and its understandable if gamblers are hesitant to try new sportsbook/casino because of the doubt that it might be a scam. So what you can do is to prove that your platform can be trustworthy by providing a good service when it comes to security, withdrawal and online support. These are just some of the important factors that gamblers consider when they're playing. Offering bonus to try your sportsbook can also attract the gamblers and to experience playing on your site without requiring them to deposit first.
Usually new sportsbook try get trust from costumer or gambler by advertising and make promoting trough signature campaign on Bitcointalk forum, but usually have new sportsbook always give sign up bonus when early gambling platform launch. But most effective with new sportsbook get positive feedback from gambler how their website keep running well although have many people access and get withdraw process instant.
To gain trust from gamblers is not as easy as we might think. Trust is not earn in a day but it takes years to work for it and the funny part is that, it can be destroyed in one day. This is the reason why why gambling platforms had lost there trust and fallen away from the reputation path. Op should try and fix it casino. Provide services that will make gamblers to come back for your casino without having to be weary of what could happen next.