So what will be the plan for these people? If they've known each other for, say 10 years, and still don't have a startup idea they want, it seems like it will

So what will be the plan for these people? If they've known each other for, say 10 years, and still don't have a startup idea they want, it seems like it will take more than 3 months, I think that's the Y combinator length, to get an idea that they are truly passionate about. Note, I'm sure that smart people can come up with many ideas in 3 months, it's the becoming passionate about it part that I have a hard time seeing. I'm guessing that people become truly passionate about say 5 -10 things in their lives, it seems odd to suspect that they'll come across the idea in such a short time and then be able to act on it in time to take advantage of Y combinator. What am I missing?