In American and English cultures, poker is one of the largest pastimes. Gambling in general is extremely popular but card games are played by almost everyone. There are literally millions of games in the world that utilize cards in some fashion. Poker cards make up for a large percentage of these games. Different people play different variations but the older crowd tends to enjoy playing for money.
The gambling industry is incredibly vast and the people and games within it are very diverse. You can walk into into an American casino and it will be very similar to a casino in Europe. Some differences can be in game variations and rules or even services. Games such as roulette feature zero pockets and the U.S. normally uses two zero pockets and Europe tends to use just one. This gives the house a great advantage. But out of all of these games poker has always been the strongest and most played.
The reason is because card games can be played almost anywhere. Gamblers do not necessarily need to go to a casino or find a poker room. Many players actually prefer to play among friends at their own homes for friendly wagers. Online casinos and card rooms also add to the excitement and diversity. A player can find any game they wish to play online and the rooms are plentiful. Live dealers and chat options allow for a smoother game. These online games are played for money just like in a real casino.