I am (and esp have been) pretty lonely, and this is it, there's no sanity tests for thoughts. In good situations, other people provide a grounding, stabilizing influence. Without them, the mind has to do this by itself, leading to some pretty extreme overcompensating and "just so" stories.
I read one analysis of those who saved/hidden Jewish people during WWII. They tended to be socially isolated people, a bit outside of society. That is what allowed them to not fall to group think and to overcome fear. (The analysis was done by some Jewish institute).
