Stopped playing it on a daily basis a long time ago but still usually log in on a daily basis to get my 10 museum cards and paints and to too keep my winning bonus at 200%.

I'm a active user but only two or three days per week... and there are guys that didn't log in the game to play it like a friend that have the PS3 on the bedroom and the WiFi didn't reach there... when it needs to update or download a game it change the PS3 to living room and after back it to bedroom again.

That's actually quite impressive since the game is more than 2 years old and is mainly played in single player.

The online lobby activity never went down since day one

How do you know for sure? Is there a daily population chart or something? 

Lobby activity is what I saw when play online and I never get low numbers of matches or users since release.

I tried the online once it was pretty boring but I do play it indirectly online a lot since I do a lot of the seasonal events.