When you tread water, you lift yourself up by pushing water down. Likewise, in any social hierarchy, people unsure of their own position will try to emphasize it by maltreating those they think rank below. I've read that this is why poor whites in the United States are the group most hostile to blacks.
All instincts immature, All purposes unsure, That weighed not as his work, yet swelled the man's amount: Thoughts hardly to be packed Into a narrow act, Fancies that broke through language and escaped; All I could never be, All, men ignored in me, This, I was worth to God, whose wheel the pitcher shaped.Robert Browning
Whatever else is unsure in this stinking dunghill of a world a mother's love is not.
An habitation giddy and unsure Hath he, that buildeth on the vulgar heart.