> Running your own mail list and custom domain isn't trivial

Regardless of whether this is trivial or not, Substack is a service, not a partner.

If one day you decide to increase your prices and work your ass off to produce more valuable content to your readers, why should Substack get more money?

If instead of sending newsletters we were talking about ecommerce (which is way less trivial) would you be ok with Shopify charging 10% of revenue?

What about AWS charging you 10% of your revenue?