So people using BitTorrent do not create a communication network in your opinion? Just guessing, as you did not mention it anywhere. It has around 200 million active users, and evennif you exclude leechers you should come close to one million active seeders.
Bitcoin vs the World: how big is btc's network compared to other large networks?
Here's my analysis: https://stacker.news/items/816200
Discussion
I didn't think of BitTorrent! Good call. Is there a website somewhere that estimates the total number of active seeders?
I do not know of any webpage that shows active user count. But you can get some info on this easily, but this probably not easily verifiable. I just expect the number to be much larger then the other examples you had here.