Y-Combinator is an edge. Y-Combinator is a valuable resource; peer review, networking, and heavy motivation. These are things not easily gained on your own. If you really need Y-Combinator to gain success, then you better question yourself and what you offer. Personally, I know my idea will revolutionize the industry it pertains to, but submitting an application to Y-Combinator is giving me the needed kick in the butt to jump on the progress train. It's been brewing for years and tonight I'm excited. I don't need Y-Combinator, but right now I want it!