Whether one needs to follow or not is up to the person's belief in the religion.
I don't think it is about whether the person belief or not because it is already there in the holy books not to seek to double money by gambling but it is by operation of the conscience to follow what is written. The people who have not fallen out of what is written will still keep to their habit of not gambling but those who have fallen out will still keep gambling until they find their own conviction not to. So the choice to gamble or not depends on where you are in the faith of what was written and many gamblers understand this but they decide to continue for their own reason. Such reason could be for finance majorly because many depend on gambling for survival in the midst of no job especially people from high unemployment countries.