Damn… I hadn’t thought about it that way, but really obvious now that you’ve pointed it out.
I wonder if it would make sense for Medium to put an upper cap on how much a single writer can earn. But then again, maybe it’s much better for them for the whole thing to be a lottery: draw lots of new writers in by selling them an unlikely dream—by blasting them with articles about “how you can also make $10,000 a month”. Probably works better than if no one could make more than, let’s say, $1,000.