steam has 8k concurrent users
If I'm not mistaken, Steam peaked at 12k players a few days ago, which is truly amazing and a very clear sign that still so many people love this game.
However, Steam counts multi- and singleplayers in the same way and it is a well known fact that the big majority of Steam players unfortunately do not play/are not interested in multiplayer.
I guess it's our job to make them realize how much fun multiplayer can be too!!