How Much of Substack Is Actually AI?

I analyzed thousands of posts from the top newsletters to find out how much of Substack is AI. Some of the biggest “writers” on Substack aren’t writing at all.

In March 2025 an alleged debate between Elon Musk and Keanu Reeves went viral on Substack. The post amassed 25,000 likes and nearly 5,000 reposts. Even today, it continues to spread. But the debate between Musk and Reeves never happened. The Substack post was entirely generated by AI.

Lately it feels like I’m encountering more and more AI-generated conte…