Behavioral finance is at the individual level

Courtesy of Kal, The Economist

Here are 7 psychology concepts showing that investors are not rational as orthodox financial economics holds. Investors have emotions and mental frameworks to process information that makes their decisions irrational, though perfectly "normal". 

But behavioral finance is at the individual level, not the group or the societal level. The title of the post linked above is clear: the biases examined by behavioral finance are psychological. At the group level, the dynamics might different, but to discover that, we need more work from the sociology of finance and crowd psychology.