Casinos have been the way for the mafia to operate legally.
Could it be a way to launder money? Jimmy "No Nose" comes in with $40k cash every weekend and loses it gambling, and "nobody knows" where a guy like Jimmy gets that cash so regularly.
[1] https://www.gamblingcommission.gov.uk/print/The-money-launde...
[2] https://moneysmartathlete.com/betting-industry/money-launder...