This was announced a day or two ago, but it seems like we never had a thread.
PCGamesN said:December was the biggest-ever month for Grand Theft Auto Online. This is stated in an announcement from Rockstar who also confirm that 2017 was the game's biggest year so far.
GTA V publishers, Take-Two, recently announced that all of their future games will have microtransactions.
Source: https://www.pcgamesn.com/grand-theft-auto-v/gtav-2017-player-countIt goes on to say that "2017 was the biggest year of GTA Online yet, capped off by an epic December that saw more players in the game than ever before." For the record, that's a four-year-old game continually breaking its own records - no real surprise, as last year it was announced as the USA's best-selling videogame of all time.