Think of a crowd. Think of a mob. Think of a mass. The collective nouns for ‘people’ mostly come with negative 
connotations because, in the English language at least, such large groups are regarded apprehensively.
If a third party talks about a crowd’s ‘mind’, then that collective intelligence is automatically levelled down, sometimes to stupidity and more often to madness (except in obscure SF or fantasy).
Think of Charles Mackay’s seminal book Extraordinary Popular Delusions and the Madness of Crowds, focusing on economic bubbles and mass movements.
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