Sometimes a decent FOSS app is created with no income flow, true, but I don't think anything on the scale of a web browser/rendering engine has ever.* All of the sizable FOSS projects I can think of have the support of one or more sponsors who have an an interest in seeing the project succeed. I'm thinking of Linux, Chromium, AOSP, Debian, KDE, Blender, and the like. About 85% of commits to the Linux kernel are from full-time employed corporate contributors.

Lemmy gets some sponsorships I think, but from non-profits. Besides that, it is supported by donations, and seemingly not enough. I was a regular donator, but I've since fallen on hard times and cannot help right now. They deserve better, honestly. My point is, we take nice FOSS projects for granted, and I don't think we really have any right to complain if they go away or wind up driven primarily by corporate interests. The work is not free.

*Come to think of it, I think KHTML, the rendering engine on which Blink and Webkit are ultimately based was started as a volunteer project. After it became a viable starting point for Apple and Google though, it was forked and primarily developed by employees of Google and Apple. I guess that's a similar story as Linux, but without the fork.