I don't know, there are some pretty big hitters on Substack (admittedly I am not inclined/able to pay to read them individually either), and I have stumbled across a lot of great writing without trying too hard. But yeah, no one is going to be living large there for the most part unless they are very lucky/dedicated/already have a big following. Saying that I see the misery porn and bropeneurs attract actual paid subscribers so there is perhaps some hope for us all, even though those markets are perplexingly always there.