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Most people nowadays don't care about sin, what they want is money and satisfaction because with money you can solve every problem in the world and satisfaction make you know why you need to live long.
It is a fact that most gamblers today are also people who worship every week or pray every day, but they prefer to continue gambling because they think that gambling is a normal activity and even though their religion prohibits it, they think that it is a venial sin - so it doesn't bother them too much.
Totally depends on a particular person on which we know that there are ones who do really care about on whats prohibited or whats been not allowed specially into their religion,
but its true that there are people who dont really care since committing out such activity isnt really that too much of a problem for them since they do able to control
themselves on playing gambling. The only issue on here on why its prohibited by most religion is that it could really be resulting into those kind of prohibition on which it is really something reasonable.
The main thing on why most people been thinking that it is really just that fine to commit such sin because they arent doing something wrong against other people which i think it is also reasonable.
Usually people who are ended up on committing suicide or having that criminal act because of too much gambling addiction.