Sherry McGuinn I am pretty sure the top earner is a certain well known “political/government” writer who writes anti-Trump rants — someone writing medium specific advice alone is not making over $1,000, let alone $19,000.
But regardless, it is not a “legend” as this person was highlighted by the Medium Partner Program earnings data in the monthly newsletter (not random speculation by Christopher Oldcorn):
August Earnings Data, Featured Authors/Articles, Top Stories by Day, and More
Blogging Guide Newsletter 2 (September 2019)
And even if this top earner never publicly identifies themselves, people making $5,000+ per month have posted earnings screenshots (and they are not even the writers of most of the top stories) so it is not surprising that there are a few making serious money.
So that is not “bullshit” unless you are claiming the MPP is an elaborate conspiracy, perpetrated by the Medium staff, consisting of hundreds of sock puppet accounts and massive fraud.
You may be right that the best writers (in many reader’s estimations) are not the highest paid, but that is a separate issue.
Regarding curation, depending upon the topic, curation can be very easy to obtain or seem nearly impossible, due to the sheer number of submissions. If memory serves, you write a fair amount of poetry, which is fiercely competitive and not especially lucrative, which may also make this seem impossible.