You will not be good at everything. Running a business requires a lot of attention in a lot of different areas. Product, Sales, Marketing, Accounting, Legal, Management and more. Each of these are full time jobs on their own and spreading your expertise too thin across them is not an efficient use of your abilities and brain power.
You will not have time for everything. There is just way too much to do when running a startup, especially early on where things happen at a break-neck pace. Finding and being able to rely on someone with complementary skills is invaluable.
But wait… Can’t I just hire people for that? Assuming you have the capital, this is true. But there are more benefits to having a direct peer than just head count.
You are not always right. Confidence is necessary in this game but having a peer to challenge your direction and thought processes will enable you to make better decisions quicker and help steer you away from the rabbit holes I know we all get into.
Focus and accountability. It’s easy to say you will be focused 110% all the time, despite that being unrealistic, just because it is your company. Having another human being that is relying on you and going through all of these steps with you is often the extra kick of accountability needed. Good cofounder’s build each other up and keep each other honest.
Startups are risky. Two (or more) brains are better than one. Mitigating and sharing risk provides stability whether its emotional or financial. This is true on a macro and micro level where quick but difficult decisions can be strengthened.
Of course everyone is different. These may not be strong enough considerations for you to give up a large portion of ownership on your idea, but I would definitely suggest thinking hard about it. I have seen many people burn themselves out by not opening this pathway earlier.
Let me know why you chose or chose not to have cofounders!