I read today that the estimated valuation of Medium is $400 million. I find that astounding. Bear in mind that Bezos bought The Washington Post, no slouch in t

I read today that the estimated valuation of Medium is $400 million. I find that astounding. Bear in mind that Bezos bought The Washington Post, no slouch in the journalism world, for $250 million not too long ago. How big is Medium's traffic? Monthly uniques? Ad revenue? Or any revenue? Where is the there there?