Have you ever tried in a lucid dream to say something like 'show me my most worst fear' or 'show me the thing that will scare me the most'
I'm wondering that if you say this because you subconcience knows you better than your concience the thing that you'll see will be terrifing.
Try it and report what you see,
I've not had the chance to try this because my lucid dreams are very short amd very blurry.