Yep, that's the problem with browsers. They cost so much to maintain that their primary contributors are earning money through other means to keep the projects going. Gecko and Chromium are open-source, backed by Google money on both ends, but even then almost all of the non-corporate browser projects are just forks of one or the other.

Other than Safari, which is closed source and only on Apple's walled garden, Ladybird is the only non-Chromium, non-Gecko browser I can think of, and it needs a LOT of work.