Morally questionable activity doesn't save a region? Color me surprised!
What's morally questionable about gambling?
Not really gambling itself, but the gaming industry. It tends to prey upon people who gamble with money they can't afford to lose. So long as people gamble with money they don't need, it's not any more objectionable than any other recreational activity people spend money on.
Las Vegas gets a little bonus from gambling: it is far enough from other large cities that people who gamble much stay in Las Vegas. The nearest real city to the Las Vegas area is St. George, Utah. Greater Las Vegas gets the hotel and motel business of gamblers. Reno is much the same. But contrast some other cities that have turned to gambling: Atlantic City and Detroit practically get commuters who don't get tired and have to sleep over in those cities.
Tunica, Mississippi is in a God-awful area. Why would anyone from elsewhere want to stay there? Memphis has much entertainment. Surrounding areas in Arkansas, Mississippi, and Tennessee are very poor. Tunica basically gets commuters as gamblers, largely from Greater Memphis. Atlantic City can draw upon Greater New York and Philadelphia. Detroit gets to draw gamblers from Rustbelt cities. Tunica?
Tunica got a boom from initial construction, but once that was over it got a low-wage, no-value-added business. It would have been better off with manufacturing.