That's why people have different religions because have different beliefs, for a country that most populations are Muslims, their laws of the land are based on the law of their God, we can't change that as that's why they believe even from the beginning. For us, gambling is just entertainment, but for them, it's a sin, we just have to respect that.
It is for these reasons that many gamblers are in countries which is not very restrictive like the US, Europe and some part of Asia, let's admit it gambling plays a big part in any countries in terms of taxes and community contribution, our brothers may treat gambling as sin but it's a big help especially in third world countries, this is one of their cash cows.
taxes from gambling have an important role in building a city if it is managed properly, now it depends on our perception of whether gambling is a sin or not, as long as we don't steal or rob to play gambling then I think it's not a sin.