Who said Familiarity breeds contempt?

This saying has some different meanings.

The first meaning is applied to relationships. If you know someone very well or experience something a lot, you stop respecting them.

The second meaning could be: the better we know people, the more likely we are to find fault with them.

Or finally this saying could mean: the more you know something or someone, the more you start to find faults and dislike things about it or them.

All these examples are about becoming familiar with something/someone.