Mikkel has a point, though - it is infinitely easier to be skeptical of other people's claims to reality than our own, regardless of the latter's merits. I would argue that for most people, their identity is to a degree tied to their understanding of the world, and so we tend to implicitly take the reliability of that understanding for granted, when there really is nothing that makes us more qualified to opine about reality than anybody else.
Indeed, our own sense of self seems so strongly tied to our assumption of the objectivity of our own beliefs that we can experience great discomfort and suffering when that assumption is eroded.
I don't think it is a coincidence, for example, that gaslighting - i.e. making somebody reject or doubt the facticity of their own experiences and memories in favor of somebody else's - is one of the most brutally effective and gruesome ways to break down another person's sense of self, to a degree that does actual harm to a person.
