More than 6,300 players, each paying an entry fee of $10,000, gathered in Las Vegas early this month for the championship event of the 44th annual World Series of Poker. The tournament ran for 10 days, and just nine players now remain. They will reunite in November for a two-day live telecast to determine who wins the first prize: $8.3 million.

Poker didn't get this big overnight. In 2003, a then-record 839 players entered the championship for a shot at $2.5 million. The winner was an amateur with the improbable name of Chris...