Okay, am I the only one who's a bit tired of hearing that every rejection is a badge of honour and the like? I mean, okay, learn from failures and all that, but they aren't badges, they're things to avoid. There's no need to sugar-coat it, sometimes your idea just sucks or is unworkable. Take the feedback and do your best with it, but being proud of it is a bit of a stretch.
I think that there is an optimal number of rejections. Too few and you don't realize all the things that can go wrong with your business. Too many and it wears down on you. We had what I feel was too many, but then we finally raised a big seed round.