The fact that there's huge amount of money in terms of facilatating underground gambling, that's where those corrupt officials/politicians are involve, if not all are being own by those personalities most of them are protectors that's why this kind of illegal business do exist, like what you have said, free will that should be provided and allow people to choose if how they wanted to be entertained, though they just need to monitor and put rules to prevent heavy addictions resulting to some crimes that might be cause of gambling participation.
Yes, it is a fact, but in no way will the solution be to prohibit, as long as they prohibit these activities it will trigger people to do things to go against it, also I do not see logic in prohibiting these activities if those who practice this must be adults, the government is not a father or mother , it is a government, it is a person or people X who have nothing to do with our lives, they are mostly corrupt politicians who in the end are useless, for these reasons there are always wars and conflicts where only the people suffer, they do not.
They just after the money and together with those who facilitate this underground gambling, they are protected of those people in power, like you said instead of prohibiting better to maximize the use of this entertainment part, where gambler can access the platform and the government will be able to earn out from the taxes that the business will provide. Instead of illigalizing which they can't stop the lust and desire of those gamblers to keep playing.