To be naive is to be unaware of how stupid and cruel other people are; but, by some definitions, ignorance is nearly the opposite of naivety in being a kind of cynicism, in being unaware of their intelligence and humanity. It seems to be a normal although unfortunate case that the great many of us consciously abhor ignorance in others yet subconsciously practice it ourselves: as naivety is apparent and well-known to inflict its damage upon oneself; whereas the alternative and the easier, ignorance, its damage upon others.
When you love someone, you end up caring about each and every person they love. When you hate someone, you end up caring about every single person who hates them.