Gambling is illegal in Iran, but there are luxurious underground casinos fully equipped for card games. Interestingly, many famous athletes, artists, and even politicians—who publicly condemn gambling—can often be seen in these underground venues.
Without those big names being involved or having something to do with that place, it will be hard for an ordinary citizen without any government backup to pull off something like that, knowing the implications if they are caught, and if somehow they get exposed and the officials who are not part of the deal for getting that underground gambling running happen to notice, the place will be shut down, and it will be hard for the owner of the place to be tracked down.
Most times in almost all societies of the world today the law works strictly on the poor citizens while the very influential and wealthy connected men can always have their way to go around it. It's not just a thing about Iran. Check all the countries where gambling is banned and as a result there exists an underground gambling centre, it's the high and mighty in that society you will find there gambling and not the less privileged because before you could actually have access into it you'll be thoroughly profiled if you fit the standard base on your status.