In London at the Bridge it is a very common issue. Also in baker street or oxford street.
I had to declare something to the police once, and there was a tourist in front of me trying to file a complaint to these people saying they robbed him from 200 pounds. But the police just laughed, as they know he will never see that cash back again. Police said, you should not gamble on the street sir. It is not legal. He screams, shouts and blames everyone except himself. But that would not solve the issue. Police says they cannot do much, as they dissapear so fast. But basically they blame the duped person haha! well it is your own fault if you risk gambling in an unsafe environment tho.