I disagree. Having a team of employees is quite different from giving up 50% of your equity.
Its been said by YC partners themselves that co-founder disputes are a major reason why startups fail. A co-founder just means a lot of additional risk.
May be if you both have some crucial skills that you bring to the table, it'd be worth taking on a co-founder. But if you can build the product on your own, I just don't see any good reason to give up 50% equity + take on the risk of disputes arising.
If you can make the product, market it, keep your customers happy, continue to improve it as competitors spring up, build partnerships, and take care of the day-to-day of running a business, all on your own, then great.
You could probably also make a fortune selling the device that's giving you an extra 100 hours in a week.
You can work hard and maybe bootstrap your way to an MVP of a product, but sooner or later the amount of work in the startup will become too much. When it does, you are going to need to build a team around you to handle the load.
The fact that you are so adamant about not wanting a co-founder is detrimental in that it signals that you are missing the point about how a company is mostly about building a good team that can execute, and second, about focusing that team on an interesting idea.