I think you're right, but only for a narrow definition of "browser". Sure, something that looks and works exactly like Chrome, Safari, et. al. would be a gargantuan effort for a sole developer. But an 'HTTP client' can take many forms and still offer value, even advantages over the existing browsers which serve a very specific remit.

A basic text browser is the kind of thing that's buildable in a year. Moreover, once you start building that, maybe you have an idea for certain features that current browsers don't do well (bookmarking, navigation) or at all (change monitoring, api integration, editing).

I'm optimistic that there is a lot of unlocked potential in the HTTP/HTML platform.