Of course the forum is international, but that number is still generated by an automatic "bot" most likely.
When the forum had difficulty last November, there were over 12,000 as shown in most online ever in the Users area. After that was fixed, we usually had well under 1000, and usually under 500. The number goes way up when a bot does rapid sign-on, over and over, and that ties up the forum. Least it seem totally weird that I would watch that, I learned after moderating on an unrelated forum. When the forum is bogged down, I look at the user numbers. It was also an SMF type forum. The owner/operator would then fix it, but beyond my pay grade. SMF makes it sound like managing a forum is free and simple, and the software may be. Keeping the forum up running and with enough storage is definitely not free or easy.
It took me about an hour and multiple tries to get on the forum, and then to not loose the link while trying to read and then post this.