Primedice goes hand in hand with bitcoin dice world, there is literally nowhere else known more than primedice, I am not entirely sure they do anything they do to get new customers anymore.
Surely, there must be some new people coming into bitcoin casino world everyday and getting them could be beneficial for the website and its investors but looking at how they are already known worldwide I am not entirely sure even the new ones have not heard about it the moment they step into it.
The only reason why they would do marketing and advertising could be to keep the customers they have instead of getting new ones, if they do nothing and just let people gamble here eventually people will leave to place that give extra, so the marketing must be for people who are already here, not to get new people here.
Most new comers to Bitcoin and other crypto usually discover gambling sites from doing a little research. They google a few sites here and there and find this thread on Bitcointalk and see the reputation they gained and the amount of years in business they earn their trust.
You need to understand Primedice can't exactly put their ads in New York City cabs or buses or air a Super Bowl tv ad like Gemini and Coinbase did in the past. Their promos are a great way to get new people to try out their site and word gets around and they gain more visitors that way.
The way people get scammed usually is when they don't do any research what so ever and find some gambling site thru a google search which might turn out to be a scam. And only when they are scammed they start to do research and discover they sent their money to a scam site.
Hence in crypto you always need to do your due diligence.