The idea gets formed in the brain. Two possibilities: either you remember it or you don't.
Then you choose to note it somewhere or not. If not, it dies and it's gone.
Two further possibilities when its noted down; the idea was either explored or not.
During exploration, did you mull over it silently or told someone?
If you told someone, three possibilities, it might be ignored, explored or it might be shot down.
If you did it quietly by yourself, you might be limited by your own judgement or you might get more interested.
If you did it quietly, you are likely to live and die with your ideas if you don't share it.
If it was a truly great one, no one would know, unless your notes got discovered by good hands.
If the idea moved you to take some form of action, at some point you will inevitably tell someone because we live in a world where we have to co-exist with others, and only through collaboration can great things truly happen.
If you care about great things.
Telling someone does not mean actually sitting someone down to tell them. It could just be out there in the world, not just in your private notes.
When you take an idea out to the world, it could change, it could morph, and it could take on a life of its own. Or it could die, too.
Would you let your ideas live a little? You never know what their lives could be.