"Korea has the most users"?
Korea's population is 51 million. Let's assume people below the age of 10 or above the age of 70 do not play this game. That would mean about 40 million people play this game if every single Korean plays the video game. Let's assume 1 in every 2 Koreans plays this game. That is 20 million Koreans playing 'Satisfy'... As we know, the video game 'Satisfy' has over 2 billion players worldwide: that means China (1,394bn) and India (1,326bn) have fewer players than 20 million?! That makes absolutely no fucking sense. The author should keep notes of his world-building because he is making the story way too inconsistent.
The sum of 20 countries with the highest populations make up 5,464bn of this world's population. If these countries had fewer users than 20 million each as this chapter suggests, that'd mean they only contributed
<200 million (or <10% of 2bn+). Meaning the rest of the world (
7,80bn - 5,64bn = 2,16bn people make up rest of the world outside of these 20 countries) must have contributed
more than 1,8bn players (at least 1,8bn: this number could be 2,2bn for all we know).
However, that would mean at least 83.3% of the rest of the world is playing 'Satisfy'. That is just not possible because that number could be 2,37bn players which got rounded into "more than 2bn players", yet the number of players being higher than 2,36bn is impossible with the current information we have. Which is why it is so inconsistent.
TL;DR: In conclusion, there is no fucking way South Korea has the most 'Satisfy' users in the world when they have a population of 51 million. That would mean every single able-bodied adult outside of these 20 most populous countries is playing 'Satisfy'.