You have to write something that is very similar to what is already popular.
Don’t try to stand out too much. Getting several thousand minutes of read time for a single post is a result of speaking to a specific audience. You’ve got to know your readers. The post has to be 90% what they expected to read just from the headline and 10% something novel, surprising or new. Also, the 10% still needs to fit into the context of the 90% they expected you were going to say.
The most popular writing on Medium is where you are simply publishing the words that other people have bouncing around in their heads already. When they read what you wrote they should come away thinking, “I would have written that if I had an extra hour to write something.” When people read your writing, it has to sound like their own inner voice to some degree.
But yes it is hard to get curated and to get lots of readers. I’ve published over 70,000 words on Medium and I only had one story curated. It’s a very exclusive club.