Well, take the risk if you wish, but why don't you just invest money in hiring people to make the product for you? Divide your time in half between both jobs, with a clear agreement with your partner that you will only spend half the time.

I just don't think that if you are a single person trying to work alone on an app that is aimed at the YC demographic that you will produce anything spectacular. When you work with other people, you'll tend to have more diverse opinions. And you will learn to juggle your responsibilites in a way that will train you for running a real business.

If you are just sitting at home alone working on your idea for one year, it's an entire year out of the 60 you got gone.