I was reading a post from Seth Godin this morning, Thriving in a wet environment, where he writes:
No software design survives a collision with the user. It reminded me of Steve Blanks’ famous 2010 post, No plan survives first contact with customers. Steve was paraphrasing Field Marshall Helmuth Graf von Moltke who said, "No campaign plan survives first contact with the enemy."
It's pretty clear that we need to get our ideas to market earlier than later. If you're concerned that someone's going to "steal your idea," think about the alternative. Is nothing at all any different?