Society is an illusion; "people" is not a singular entity.
Imagine a loaf of sliced bread: so long as the pieces are fairly consistent and sound, it can resemble a loaf.
If one or more of the pieces is unsound, irregular in shape or consistency, the illusion of a singular loaf breaks.
It isn't the nature of "people", it is the imperfect nature of the metaphor of "people" itself.