I'm one of those writers earning more than $100 for half a year in a row now. Not much more than that. My highest earning month was still below $200.
But I do wonder. Your story makes sense, yes. But to me it also says that Medium is having a bit of tunnel vision and having problems spotting the gems in the big pile of work offered.
Are the big earners also the ones well-known, started early on Medium? Are they favorites? Do they remain favorites just because of their names? Do people in certain publications receive more atention from the Medium-editors than others? Are American writers the only high-earners?
I just wonder...