I've also had the same experience on my second product. Someone made an off-brand copy of about 18 months of work (testing marking, making prototypes, etc) righ

I've also had the same experience on my second product. Someone made an off-brand copy of about 18 months of work (testing marking, making prototypes, etc) right down to cloning my client libraries and removing all attribution. It was gut wrenching at first. I couldn't agree more with your last point. Keep doing what you're doing - but more specifically, focus on solving the problem you have identified and studied. Chances are that you understand the needs of your market better than the copycats. In my case, the ability to meet the needs users trumped my copycats ability to copy my progress.