The Asch Experiment: The concept of persons wanting to conform to the majority opinion of the group (even if the opinion is clearly wrong) . This is part of what leads to wrong buying / selling decisions

During the 1950s Solomon Asch conducted and published a series of experiments that demonstrated the degree to which an individual’s own opinions are influenced by those of a majority group. Demonstrating how a “normal” human being can be pressured into unusual behavior by people they deem as authority figures, or by the consensus of opinion around them.