A human group transforms itself into a crowd when it suddenly responds to a suggestion rather than to reasoning, to an image rather than to an idea, to an affirmation rather than to proof, to the repetition of a phrase rather than to arguments, to prestige rather than to competence.
This is not the 19th century, where actors are expected to play completely opposite roles. We're not typecast, but we're brought in because somebody thinks that it's a good fit, so you make it a better fit.