First, thank you very much for detailing your Y Combinator experience with the rest of us; you will no doubt help out many other startups planning to apply to Y

First, thank you very much for detailing your Y Combinator experience with the rest of us; you will no doubt help out many other startups planning to apply to Y Combinator. During the entire interview, I imagine PG and his partners were likely analyzing and processing your idea, your capacity to execute your idea, and your potential to succeed compared with the potential for other top-tiered candidates to succeed. Also, they were likely looking for signs, any sign (based on prior failures), that were predictor of failure. In my opinion, you were likely turned down because either they weren't convinced that you (along with your idea) have the potential to succeed more than the candidates they were considering, or your case showed signs of potential failure. Note that the signs of potential failure is not necessarily reflective of you or your idea, it is simply based on actual factors that Y Combinators have seen in startups that had eventually failed. I have read about this from PG himself right here on HN. If Y Combinator turned down a potentially primed-to-succeed applicant because the applicant did not convincingly answer one question (while being very convincing on all the other questions), then I am definitely mistaken about all I have read about PG and Y Combinator. These chaps are well-reasoned and thoroughly experienced investors, I don't think they will turn down a potential DropBox for missing one question—well, I hope not.