Yeah, the lack of feedback (and not being embedded in a motivated team) is a very big downside. In my case, I responded by distancing myself a little bit from focusing so much on success at the one "big" thing I was working on, and focusing more on enjoying curiosity, exploration, etc. The app I've created probably falls in the "tool" category more than "product", and I spend (waste?) a fair amount of time psychologically prepping myself for marking it as a failure. On balance, I still feel like it's been a good move for my life, but of course the experiment is ongoing...