How many people can live like that in any practical sense? Everything I've ever read about motivation, learning, flow, and mastery holds quick and direct feedback as the most central necessity. Applied to software development, hence we prefer fast compilers over slow, unit tests over integration, working on a desktop over an SSH connection halfway around the world, frequent releases, etc.

It sounds like you're not being sarcastic. So let me say that when you're working on something that almost surely has zero practical impact over the course of your lifetime, and the only possible benefit to society is the advancement of the state of our knowledge, a lack of enthusiasm from your peers can be gut wrenching no matter how mentally resilient you think you are. No one does math solely for appreciation from people they admire and respect, but the lack of it, even in the short term, can be very hard on a person.