This isn't my speciality, but I did ace a graduate level course in the mathematics of dynamical systems.

Your claim just isn't so.

There are systems with many independent, interdependent variables that are not chaotic; there are systems with just one independent variable which are chaotic.

Informally, a system is chaotic if arbitrarily small changes in the inputs result in large changes to the outputs after a finite period of time.

Many real world systems are overdamped - the reverse of chaotic, even large changes to the inputs result in little change to the output.

A classic example is a big boulder standing on the ground. It's subject to countless forces, from rain to birds to humans climbing it, which result in a tiny perturbation and no net change.

If an earthquake knocked it over onto its side, there would be a state change - into an even more stable state.