Bettor

In fact, as Ambrose Hammer places the cage on our table and then sits down beside me, Mindy approaches us, and says to Ambrose: "Horse players, yes," Mindy says. "Wrong bettors, yes. Dogs and song writers and actors, yes. But parrots," Mindy says, "no. Take it away," he says.

Source: wiktionary

Still others, chasing the mirage of vast riches bettors think are there for the taking, seek information or tips from any and all, despite all omens, silent writing on the wall and dire predictions about their fates, like the title of Damon Runyon's book All Horse Players Die Broke.

Source: wiktionary