Simplicity arises from complexity
Phenomena with probabilistic outcomes can seem chaotic and unpredictable on the microlevel, but at the macro scale their trends become clear.
 The law of large numbers: as the number of trials approaches infinity, the relative frequency of observed outcomes will approach their probability.
 Sociology: Individuals can make strange or unpredictable choices, or have uncommon outcomes, but at scale systemic influences on those choices become visible.
 Quantum mechanics is a little unhinged, but newtonian mechanics is pretty simple and makes sense.^{1}
See also complexity from simplicity.
Footnotes

As long as stuff isn't moving too fast or slow and isn't too big or small. ↩