Entrepreneurs are nothing if not a confident bunch. We tend to really like our ideas, especially those ideas that won't leave us alone.
But one thing I also know is that people generally have neither the time nor interest to steal your great idea. They are busy with their own lives, careers, and businesses. And the idea of nabbing someone else's idea and putting the necessary time, effort, and money into it to make it a go, I find, usually makes really ripping it off a non-starter. I think most people are generally honest, too.