People that are on gambling addiction like to satisfy two things, their feelings and their desires, once both are satisfied in their early bet, it their early bet or early days of betting, they might become addictive, unless they have someone who they can trust that will tell them when and how to stop, if not they will always look forward to playing again and again.
They wont be satisfied with their first bet.
Thats who humans function. They always want to make money by the easy way and that is gambling. Who wants to work their asses off all day long? Funny thing is that the second one is actually the safer one leaving out occupational hazards. Addicting gamblers is easy because they are having a brain that does not do any logic or reason and being lazy these modalities have been shut down long back. Give them an impetus to gamble more like a small promo or a lucky bet and they will immediately get addicted to the site.