I tell everyone. Especially people who I think can help or be able to give meaningful insight. My experience was that everyone has ideas but you can't tell a g

I tell everyone. Especially people who I think can help or be able to give meaningful insight. My experience was that everyone has ideas but you can't tell a good idea from a bad one before executing on it. So there is no danger in anybody stealing the idea. Because you probably stole it yourself. A startup idea, which is probably broad, is different from an implementation idea. Those I tend to tell only trusted people about and only to get their feedback.