~ But these days people are more concerned about making profits, they don't care who's playing, they will tell you if I don't allow him to play here, he will definitely go use the online platform. ~
I don't know how it is in your country, but normally such casinos could be fined or even closed. It's similar to selling alcohol or cigarettes to those who's underage. No matter how much you concerned about making profits, you shouldn't do that.
Also, like you said, "gambling must still at least possess that sense of decency". It's immoral to allow young people, people who don't possess certain knowledge essential for safe gambling to play games of chance at your place.