This a great question, but harder to answer than "How did you acquire your first 100 users?" and probably more important. Besides an obvious pain (like many us

This a great question, but harder to answer than "How did you acquire your first 100 users?" and probably more important. Besides an obvious pain (like many users saying X is bad), users usually become indifferent and just never come back. These users will likely never give feedback unless they've had an abnormally bad experience. Whenever you lose users, it's painful. But could be a good thing if they weren't your target since you may waste time servicing them or building features they say they want.