The old deal on Medium was that you could host content there and they would then promote your article across their network. Often that promotion could bring thousands or tens of thousands of readers (I've run a pub there for four years and I'm basing the numbers on that).
Then Medium switched to focusing on a subscription service which also came with a divide between articles that are inside the subscription service and those that aren't.
If you post outside the service, you get free hosting in exchange for Medium running "recommended stories" at the bottom of your post. These are essentially ads for the subscription service. But they don't promote your article or bring you any extra readers other than the ones that you bring yourself or who come through SEO. Obviously, this is a much less appealing deal than it used to be and so there's a sorting out where a lot of people who want to post outside Medium's subscription service are leaving.
However, if you post within their subscription service you get a pretty good deal. You keep your copyright and could republish elsewhere. Medium will promote your article to their readers. You'll still get SEO. You'll make some amount of money, not usually life changing money though especially if you have a programmer's salary. Also, more and more, you're likely to run into an editor who will at minimum offer to give your piece a copy edit and sometimes work with you on how to make your piece even better.
But does medium have readers? I mean, I read medium articles when they appear here on HN, but I’m not really a medium reader, and unlike personal blogs, where I will bookmark you if I find you interesting I’ll never come back to a medium author unless it’s by chance.
I mean, that’s as anecdotal as it gets, but I’ve never been very unique in my media consumption, so I’m fairly certain I’m not alone in this.
I'm sure there are plenty of people like you who aren't Medium users, but if I understand your question, you're asking how many people there are who are dedicated Medium readers.
I'm saying, yes, obviously there must be a lot because when we publish articles they get read by people from within the network. I also sometimes see my own stats split into web vs. app and the app numbers are about equal. Only dedicated users would be using the app. Then on top of that the money is coming from paying subscribers, the most dedicated type of user.
I'm not that interested in what the total number is across Medium because what actually effects me is how many show up at a given article. It's common to get thousands or tens of thousands. The best article I ever published got 1.1M total views with 407k views from within the Medium network. HackerNews or other external sources that drive you to Medium get counted as external views.
Oh, I forgot one of the most important changes in the deal. If you want to post inside the subscription service you can't include Calls to Action (with some exceptions). That's a huge cost for a lot of authors who are only writing in order to promote other things or collect email address. It's generally been a good deal for readers though, who are seeing less marketing pieces in their feeds.
Then Medium switched to focusing on a subscription service which also came with a divide between articles that are inside the subscription service and those that aren't.
If you post outside the service, you get free hosting in exchange for Medium running "recommended stories" at the bottom of your post. These are essentially ads for the subscription service. But they don't promote your article or bring you any extra readers other than the ones that you bring yourself or who come through SEO. Obviously, this is a much less appealing deal than it used to be and so there's a sorting out where a lot of people who want to post outside Medium's subscription service are leaving.
However, if you post within their subscription service you get a pretty good deal. You keep your copyright and could republish elsewhere. Medium will promote your article to their readers. You'll still get SEO. You'll make some amount of money, not usually life changing money though especially if you have a programmer's salary. Also, more and more, you're likely to run into an editor who will at minimum offer to give your piece a copy edit and sometimes work with you on how to make your piece even better.