EU4 stays niche. There is 1M+ sales, but probably around 100k regular players due to the difficulty of the game and the time it takes. These players all have several hundreds, if not thousands of hours of gameplay. But this is still a relatively small number of hours spent by the entire community.
This is a lot, but if I remember correctly LoL has 60M player
daily, and around 200-300M total players, who also played way beyond the 100 hours mark for most of them. There is a pretty big difference between mainstream games and games like EU4.
Edit: I just checked LoL. Couldn't find recent stats but they said this in January 2014, which is A LOT of time ago:
- Over 67 million players battle it out in League every month
- More than 27 million people play at least one game of League every day
- Over 7.5 million players simultaneously play League during daily peak hours
You would guess that this is around twice as much now
