People who are struck by inspiration sometimes become secretive and paranoid. They think that people everywhere are trying to steal their great idea.
In practice, there is no shortage of ideas in the world, and remember this: only you can see the gleaming halo that surrounds your specific idea.
Even if you wanted to give your idea away, it's not a sure thing that anyone else would see the value in it.
It's a good idea to keep your inspirations private anyway, as I explained yesterday. But unless your previous ideas have consistently made hundreds of millions of dollars, it's not likely that spies are hiding in the ductwork trying to nab your new idea.