To me this sounds just like someone not being a good developer.
As a freelance developer myself I know what value I offer my clients.
I've seen so much code from others in the last 15 years, that I can tell the results will likeley not be equal. I am proud of my work and I deliver well documented, stable and easily maintainable software.
If a bad paid dev can do the same job as you, I doubt your abilities , disciplin and passion
Marketing is the real differentiator. If people don't know why your products rocks then they will never find it or buy it. Anyone and everyone with a side product must understand that to be successful.
You said a Ukrainian could do your dev job for a fraction of your fee, I totally understand but could you clarify why the same isn't true for outsourcing marketing?