Sports betting dates back too over 2,000 years ago. It started with the Greeks, who first introduced the Olympics to the rest of the world. They also hold some of the earliest records of betting on athletic events.
Betting later spread to ancient Rome, where it was adapted and legalized. Romans mainly took part in gladiator games, and when the sport ended, gambling survived.
Betting later spread to England, with horse racing being the most popular bet on sport. It was from here that sports betting spread to the rest of the world.
Basically, sports betting is a popular past time among many people and one that is continually growing.