[onion2k]

Experienced people don't keep their ideas to themselves. They don't tweet about them or write blog posts about them, but they definitely do discuss them with their peers, networks and mentors. That's the critical point. You should tell people whose opinions you trust and value because without their input your idea is worth much less, and the chance of them stealing the idea and executing it better is absolutely tiny. If you genuinely trust someone there's no need for an NDA.

Plus, the number of times anyone has been burned by not having an NDA in place is probably a million times fewer than a person has been helped by someone they shared their idea with. Sharing is helpful far more than it hurts anyone.