TIL Patreon's estimated revenue in 2021 is $160m, and Substack's is $11.9m.

Anecdotal but I don't know anyone using Patreon yet know tons on Substack. Would have assumed less of a delta.

cma.xyz. Founder /paragraph, ceo /mirror, previously at Google & Coinbase 

I think part of the problem are the products' user bases. 

Substack has a huge free writer base, and they think of it as just a platform to manage their free newsletter on. 

Patreon is used by people planning to charge their community and can be flexibly applied to any type of community. Much larger opportunity.