Competitors may come, but they'll likely have to overcome a higher barrier (to entry) than if your problem required a trivial solution.

Think medical devices vs iphone apps. Problems in the medical field are not secret. But they typically require a novel solution, five or more years and a team of experts to implement. Potential competitors may well know exactly what you're doing but they'll have to overcome barriers on multiple levels: time, funds, patents (a big one), expertise, etc.