gambling and scamming can be the same if the odds are tweaked.
Not many gambling sites can survive of they manipulate the odds. People will find out within hours and the news will be spread like wild fire. Just search here in Bitcointalk about such incidents.
Although they are all bigger or smaller scams, they all survive because their customers are either mentally incapable of spotting the scam, gullible, naive - or suffer from gambling addiction.
They all manipulate, that's their very nature and sole source of revenue.