When people ask why South Koreans dominate games such as League of Legends and StarCraft II, the first answer I give them is infrastructure. No, South Koreans aren't superhuman or genetically better at playing video games than their global peers. It's simply that in South Korea, the famed 'Mecca of esports', professional video-gaming has been mainstream for over a decade.
The reason why South Koreans dominate in League is the same reason why the United States has been the center of the basketball world for almost a century. When you grow up as a child in the U.S, it's nearly impossible to avoid a basketball court. Regardless if you're interested in the game or not, you're surrounded by the game -- either by having to play it during school, or finding a hoop at a playground near your house. Kids in America grow up with LeBron James and Chris Paul plastered over their advertisements. Even if only a finite amount of those kids exposed to basketball with the required talent and drive decide to play the game, the United States will still produce more talent than a country without the same infrastructure in place.
For the youth in South Korea since the early 2000's, they've been in a world where the norm is people playing video games in large stadiums on television. StarCraft: Brood War took over the nation at the start of the 21st century, ingraining itself in the country's pop culture. The best players of the game were treated as sex symbols, dressed up in stylish outfits in advertisements to bring in a strong female audience that would take over studios to support their favorite players. The games were broadcast on cable television, with OnGamenet (OGN) and MBCGame (MBC) showcasing esports to the general public like ESPN does with basketball in the United States.
Atop of having the games on television, the internet cafes in South Korea, known as PC bangs, are a staple of teenagers in South Korea. Similarly to how kids in America can't go a mile without running into a basketball hoop, it would be difficult to find someone in South Korea who hasn't been to a PC bang. For a low hourly cost, teenagers can play their favorite online games like StarCraft with their friends, finding a safe haven from the stresses of school. Although being a professional gamer still isn't seen as a desirable job for a lot of parents, it's still more accepted than in the west. The former esport stars of over a decade ago are still relevant today, with a few of them now variety stars on South Korean television. It's easier to go down the road of esports as a 17-year-old kid when there have been people before you that've done it successfully.
North America, Europe, and the rest of the world are slowly catching up to South Korea in terms of infrastructure; teams are starting to mirror themselves on how the east build their professional teams with coaches, support staff, and structured practice schedules. But, even though esports is growing around the world, the location of the heart of esports isn't changing anytime soon -- in the middle of South Korea, where 'the future of esports' is merely their present.