A 50/50 split means your non-technical contribution is worth the same as building the entire product, top to bottom, front to back. Having an idea for a certain software feature takes only a tiny fraction of the time it takes to implement that feature. So if you're just the "idea guy" or even the "vision guy," you're going to be putting in way, way less work than the technical guy.
So, what more can you do for the company? Although building the product is a huge endeavor, there are many smaller, administrative tasks involved in running a business. M of these are dreadfully boring compared to building the product, but if you want to justify your 50%, you probably need to take them all on yourself. Here are some of those things:
- Accounting and taxes, whether you do it yourself or hire an accountant.
- Dealing with lawyers. It doesn't stop with the operating agreement.
- Getting money, one way or another. Even though you're not paying your programmer, you'll have plenty of expenses.
- Paperwork: bills to pay, forms to fill out, forever and ever until your business ends.
- Choosing and applying for insurance providers, credit card processors, bank accounts, lines of credit, etc..
- Managing ad campaings.
- Blogging and promoting your blog.
- Hustling the tech press.
So now, as the business guy, you're thinking, "I can do all that!" And you certainly can. But that's not enough. You have to be _good_ at all those things to justify your split with an above-average coder. And I know from experience that these tasks do require talent and skills to do well.
For example, hiring lawyers and accountants may seem like a no-brainer. They're the experts; you just have to pay them so you can lean on their expertise, right? I'm afraid it's not so easy. Unless you hire true superstars--whom you probably can't afford--they're not just going to "take care of it for you." Getting the most out of hired experts like lawyers and accountants is a skill in itself, and you can easily mess it up. If you're skeptical, just read about all the startups that got into trouble despite (or because of) the advice they received from experts.
And that's just one example. The same applies to all the business tasks I listed above. So sure, you can do them, but you also need to have some unique talents for those things if you want to earn the same amount as the guy who's building the entire product.