When you look at the moon, whether you going to estimate it's size or measure it or withhold judgment, you know it's there with a size. We see ourselves from a distance, and we have judgments we gained from society, some of it true, some it false, some of it reasonable, and some of silly non-sense. We can't define who we are, we go astray, but we do tend to know things about ourselves and also ignorant about things about ourselves, and also have false beliefs about ourselves as well.
So who you are, is where exactly? If it's you who makes it, what happens if you are wrong about something about yourself. Physically you exist regardless, but who you are, needs an accurate judgment to exist. Or otherwise, it's a fantasy with no reality, nothing but an illusion.