Ask HN: who do you tell your ideas to?

I have a friend who's been harbouring a reasonably good startup idea for the last 2 years. He's a solo-founder and is cautious in telling people his idea: perhaps he's told about five people all up. Personally, I believe he should take the opposite approach and pitch to anyone who will listen.

But it got me thinking: what is your philosophy for telling other people your startup idea(s)? Do you wait until a prototype is built? Or do you start pitching to everyone you meet from day one? Of course it differs from startup-to-startup, but it would be interesting to hear peoples experiences.

My personal belief is that people need to be force-fed anything that will require them to change a part of their life. And also: taking risks is an unavoidable part of being an entrepreneur. Thusly, I pitch every one of my ideas to anyone who will listen, prototype or no prototype.