Chaotic in the sense of sensitive dependence upon initial conditions? Because human actions depend upon a large number of factors influenced heavily by their environment and their life experiences. It's far harder to find systems which are not chaotic than ones which are. Even the classical 3-body system interacting under gravitation is chaotic.
And while, yes, there is definitely good work being done in studying dynamic systems, applying those things to human beings is very difficult and dangerous. We already often face situations where humans are expected to conform to a limited set of predicted responses rather than the system being seen as flawed for failing to predict all possible responses. And human beings react very, very poorly to being restricted in these ways.
I totally get what you're saying about the unpredictability of human behaviour. But I don't see the connection to this particular system. It could totally be chaotic if it was modelled as a dynamical system, I don't disagree with that, but as far as I can tell they approached it using neural networks...
Chaos isn't an intrinsic behaviour of humans, it's a property arising from specific conditions in a dynamical system. I do think there's been interesting results in trying to model human behaviour (http://www.wilmott.com/pdfs/090610_mandelbrot.pdf), but like you I'm hesitant to apply these mathematical models to us irrational humans. Anyway, I'm just being a pedantic math nerd.
P.S. Sensitivity to initial conditions alone does not imply a dynamical system is chaotic.
And while, yes, there is definitely good work being done in studying dynamic systems, applying those things to human beings is very difficult and dangerous. We already often face situations where humans are expected to conform to a limited set of predicted responses rather than the system being seen as flawed for failing to predict all possible responses. And human beings react very, very poorly to being restricted in these ways.