Yes, Jim, I have invested a lot in Medium. And I could invest that same energy elsewhere where I have better luck or an easier market.
I've noted that you write the kind of things that I don't. Yes, there are virtual beginniners on Medium, and they are doing well, but they are writing things that appeal to the appetite (how to make money, how to raise your self-esteem, how to get lots of followers, etc.) I don't write those type of things.
65,000 writers have joined Medium in the last few months. Medium is over-subscribed by writers, and many readers have left for the same reason I am - the quality of articles has gone down.
You are absolutely correct that Medium has high domain authority, but that continues whether I renew my membership or not, and I can possibly earn through affiliate marketing.
As you can see, most of my readership comes from Google.
Yes, it's possible that one of my articles goes viral, but considering the kind of thing I write - it's not probable.
If I knew for certain, it was a good investment, I would stay, but I'm not sure.