Business is business. Some are good at it. Others not so. That said, it is possible to write your own software, especially for mobile apps, and have it sold for you in the mobile device app stores. The cost to entry is not too high, and if your app gets traction it can make you a lot of $$.
Do you have the skills to create a commercial software product?
Do you have an idea as to what the product should be?
If so, develop it and distribute it through the MS/Android/Apple store(s).
Do you have demonstrable specific sales skills that would encourage a software developer to pay you for selling their product? If their product is suitable for an existing app store then what value-added can you bring to them?
The big question is whether you can get into the industry with a completely new application. If other companies are so far entrenched that it would be very difficult to compete, reselling is a good approach.
However, as a reseller you'd need to bring something special to the table. Usually this means customization services that would be too expensive directly from the vendor or intimacy with the product that rivals the vendor at a noticeably lower cost.
As an example, the company I work for is a hybrid. We primarily resell a few enterprise applications, but also write customizations and custom smaller applications as the need arises. Our unique offering in reselling (as there are many other resellers) is:
Quality, quality, quality. A lot of customers come to us because our solutions are simply better.
Responsive and expert support for our solutions.
Custom coding for the resold software to fully meet business needs.
Completely custom software as needed to round out solutions.
Either way you need to make a name for yourself. Simply reselling and installing out of the box applications won't be super successful. One of our claims to fame is our engineers being able to accomplish things that other resellers deemed impossible. Another is that our support staff themselves are or at one time were engineers, so any support ticket is worked from a high level even at tier 1.