It's part of their culture. Traditional gambling games in the Wild West included faro, three-card monte, and the ever-popular Texas Hold'em poker game. These games were not restricted to saloons and gambling houses, often spilling out into streets, camps, and even church meetings. Texas Hold'em poker: Not much has changed since then.
Arizona was much the same. Although gambling and prostitution were never officially "legal," they were wide open because nobody cared about them. My hometown, in north central AZ, had mining and an Army fort as its main employers. Miners and soldiers = gambling and prostitution. Both flourished here into the 20th Century, seldom closed down by "The Law.".
