Another angle is the Medium lottery. About a quarter of my feed comes from writers who have made attained some level of success on Medium. I think Medium deliberately give some people a high priority on the feeds to entice the feeling of "I too can get lucky." Good for the people selected in this way.
Anyways, the math does not work. One writer complained of her $800 a month Medium paycheck. It wasn't enough. But she would have to bring in, according to my math, 192 readers a year to pay for that paycheck.
When I first joined, I noticed that half the Medium contributors had been here less than one year. To me, that was a sign that many people try out Medium and find it can't deliver what they want. Then they move on.
These days, I am reading good articles from people with less than 100 followers and/or less than one year. It seems like I have become a veteran! But with 39 reads on my last article, can I call myself that?
In other political internet forums I had participated, there was no illusion that postings were going to lead to something greater (most of the time). These contributors knew their work was going to die shortly after the post.
Some political posters (including on Medium) believe their postings are contributing to a better world. But I think it's mostly arrogance and feeding their own ego (which I might be guilty of). Another version of self-interest.