Even though your idea is ambitious, you might consider nights/weekends to work on it - you know the whole "a journey of a thousand miles begins with a single step" - get something together and see if you can raise some funding - you never know. There's a lot of money being throw around right now.
I think YC is setup so it attracts those who are willing to go out on a limb for an idea, since (and this is a guess) they might be the most likely to persevere through the rough patches and stick with their idea until it succeeds.