[nestorD]

Sharing ideas led to other people playing with them and, sometimes, finding significant improvements you have not thought about. I have seen this being such a benefit that I now never keep an idea to myself.

However, there is value in keeping some ideas secret / private. My preferred approach is to have brainstorming groups and partners in the various domains I am interested in: whenever I have an idea that seems interesting I share it with them (usually one on one as it leads to the deepest dives) and they react to it. They do the same leading to a lot of cross pollinating.