This is something you see with Twitter, as well. A lot of the extremism on Twitter drives a lot of journalists and politicians. But most Americans are not on Twitter.
One thing that indeed sticks out is that if you take a particular topic and inspect the leaders in that topic, many have more than 100K tweets. That's over 270 tweets per day if you'd compress it to a year.
A quick glance at these leaders' timelines shows that they tweet all day every day, you need to scroll endlessly to just catch up with a few hours of their activity. It's basically all they do.
On the other end of the spectrum are indeed people that never tweet or hardly ever tweet.
And there's an important in-between category. People that do use it frequently, mostly commenting on those extreme leaders, yet for some mysterious reason, they can never get above the magical number of 2,000 followers themselves. They are basically the cannon fodder for the Twitter elites. It is them that like, retweet and comment, all to boost people already winning at the game even further.
Somewhat related, I encountered this curious phenomenon myself accidently when trawling through CBC news articles in the lead up to the latest Canadian election. I casually scrolled through the comments for some guilty pleasure entertainment, and found the same few commenters posting on every single article. I took a peak at the profiles of two commenters who were flighting over their political view points and found they each had over 100k comments.... On CBC news articles....
[1] https://www.pewresearch.org/internet/2019/04/24/sizing-up-tw...
Probably "Most of What You Read on the Internet is Written by Insane People"
https://news.ycombinator.com/item?id=18881827
https://www.reddit.com/r/slatestarcodex/comments/9rvroo/most...