It sounds like gate-keeping too me; like JRE saying there are only 250 real comics in the world or @LPNH deciding who is Libertarian enough on Twitter.

We probably can't agree on a number. But I think it's obvious that they'll never be large enough in modern times to affect anything besides a niche message board in some corner of the Internet.

Just like QAnon. /s

I went looking for genuine flat earthers in the late 90s. There were far more people complaining about flat earthers than there were actual flat earthers. I could count the number of them I found on the fingers of one hand, and they seemed like they were probably mentally ill. Back then I would say they were mainly an urban legend: "did you know that some people still believe the earth is flat!" "in this day and age? How shocking!". Its mainly just an outrage-bait meme.

I'm convinced that almost all flat earthers, even the few "true believers" got their belief through reaction to the mainstream. Its not really a belief about the shape of the earth, its more a belief about how you can't trust the status quo. If everyone just stopped complaining about flat earthers, they'd all be gone within 20 years.