I went through YC as a solo, first-time founder and I would not recommend it to anyone. Despite working the hardest I have ever worked in my life, I barely made it through Demo Day, and my Demo Day presentation was not exactly riveting. Furthermore, after Demo Day, you still have to continue building the business.

Solo, first-time founders will undoubtedly lack the emotional support systems necessary to give them even a baseline sense of sanity and the mental clarity to persevere. They are far more likely to make stupid and irrational decisions. It was not until I found a cofounder, long after YC, that our company began to behave even remotely like a normal company.

Having a cofounder to share the load with has unforeseen compounding value that one does not have the awareness of to offset in their first company. Maybe in a second or third company you can pull it off by planning around the repercussions of being a solo founder. Unfortunately, without previous experience, you will have no idea how to do that.