Your incentive would be that your product is better and sells more, unless and until everyone copies it. As long as the extra profit exceeds the cost invested, it's worth it.
You're claiming there would be no innovation at all unless there's IP.
How did we innovate for hundreds or thousands of years before IP laws, whether the wheel, ironmaking or any other technology?
To flip your question on its head, if IP laws prevent your innovation from reaching everyone, the benefit to society from this innovation is reduced, and that's bad.