"But how do you practice answering tough questions?"
And how do you handle answering so many of them, fired at you all at once from multiple people in the span of 10 minutes? Every description of the YC interviews says that's the hardest part and I can see why, for the same reason that grad students say that defending their phd thesis in front of a panel of professors is one of the hardest things they've ever done.
"... And how do you handle answering so many of them, fired at you all at once from multiple people in the span of 10 minutes? ..."
I don't know. I'd say learn to identify the questions you can answer as best you can. This is what I mean by having some form of roleplay, verbal, improv skills. Pick the Q's you do know, pick the ones that are important to your product.
And how do you handle answering so many of them, fired at you all at once from multiple people in the span of 10 minutes? Every description of the YC interviews says that's the hardest part and I can see why, for the same reason that grad students say that defending their phd thesis in front of a panel of professors is one of the hardest things they've ever done.