But talking about the odds is misleading, because this pool is a mix of a large number of people for whom the chance is zero and a small number for whom it's quite high. So if you're another Drew Houston (who was a single founder when he applied), the odds are very good.
The next morning, on the train back to Virginia, hung over, somewhere in the middle of Connecticut, I get a call from Paul. He says, "I'm sorry, we made a mistake. We don't like your idea, but we like you guys." We got off the train, and I was able to sweet-talk the Amtrak lady into not charging us to turn around. In our conversation, Paul said, "You guys need to build the front page of the Internet." That was all Paul, and that became Reddit.
When drew was first applying to YC I didn't know him. But I'm going to presume that, like most young people, 6 months or a year is a lot of time for personal growth.