The danger of working on an idea that isn't properly validated is much greater than the danger of having good ideas stolen.
When I was a young environmentalist, I was very concerned with the problem of toilet paper waste.
I wasted hundreds of hours working on a reusable Loofah + Bidet system, it was a product that absolutely nobody wanted.
Are you laughing? Because its not a joke.
Tools like this one could have helped me move on to a better idea, and saved me a lot of time and heartache.