The creator started the project 5 years ago because people around him without technical ability wanted a DNS ad blocker, but didn't know how to setup pi-hole. His peak MRR through Patreon was 13$, and he received one or two separate donations of ~10$ every month as well. The servers alone cost him more money than he received.
Dutch source: https://tweakers.net/nieuws/191950/openbare-pi-hole-adhole-v...