The recent surge of players getting into Final Fantasy XIV can be easily explained. However, it looks like the game hasn't yet reached its peak, as the number of in-game players keeps rising to new highs. Now with three expansions (Heavensward, Stormblood, and Shadowbringers), Final Fantasy XIV has amassed over 22 million players, making it one of the most popular MMORPGs of all time. From then on, the game has grown exponentially as each expansion has attracted more players to its universe. Initially criticized for being on unfinished state when it launched in 2010, the game was re-released as Final Fantasy XIV: A Realm Reborn in 2012 in much better shape.
In context: Final Fantasy XIV's success story looks like it was taken from a movie.