Underground gambling is not for gentlemen, they wouldn't fit into such a place because if anything happens to them they're on their own. I wouldn't go near where they gamble underground because if anything happens to me the first question that the people who knows me will ask is what I was looking for in a place like that. From the name underground gambling it sounds like underworld gathering and we know that people of the underworld are criminals. None criminals that visits underground gambling must be gamblers that are looking for extraordinary thrills, to feel danger upon risking their money.
Something has taken you in the wrong direction with underground gambling. Why should there only be criminals there? Why do you think so? This is a very strange reasoning. I have seen many such establishments where people with high social status and even those who hold high positions in the government gather. You have some kind of one-sided and limited view of this world. You should reconsider your point of view in a broader range.