I'll just tell you why I won't pay for this, but would pay for something like the NY Times or my local newspaper. I care to know what's going on, in general. I'm not a new junky, but I read headlines from a bunch of different places, and sometimes the entire article. Paying for a place with original reporting on a bunch of different topics appeals to me. What's that old saying, a mile wide and an inch deep? That works for me.
Paying to read one person write about one topic... not so much. I already get a bunch of free newsletters from a bunch of different people on a bunch of different platforms. Someone would have to be REALLY special for me to pay to read their emails. I can't imagine there's more than one person like that.
That's just me, of course, there's probably enough people out there that are willing to pay for a bunch of special emails to keep substack going.