David Rieff has an article on the relationship of crowds to morality over at Big Questions online.
The Gospels seem to contain an implicit commentary on the psychology/morality of crowds. The bad things that happen to Christ generally seem to happen in the context of crowds; the good things happen when Christ is dealing with people one on one. The archetypical case of the former, of course, is the mob urging Pilate to condemn Christ. Then there is Peter's rejection of Christ three times in the context of the implicit mob hanging around Christ's trial before the Sanhedrin. But there is also the rejection of Christ in Luke 4:16-30 and his frequent encounters with groups of Pharisees. On the other hand, when people respond to Christ, they generally do so as Kierkegaard's Individual, separated from the crowd, e.g. the woman caught in adultery in John 8, or the centurion.
I'm sure someone somewhere has done a thesis on this.