The emotional drain came as a bit of a surprise to me, and I am not even invested much in this forum or the idea of making a career via YC. I too have built and exited startups previously (without the warm embrace of an incubator) and some rejections from dealing with investors do happen due to the nature of the game but I cannot remember it ever having felt hostile in the way submitting to a black hole and receiving an automated form letter response from it does.