Bandwagon Bias

The bandwagon bias refers to the tendency people have to adopt a certain trend-following behaviour or investment based on the perception that others are involved.

See madness of crowds, bubble and market mania.

References

1. Leibenstein, Harvey. "Bandwagon, snob, and Veblen effects in the theory of consumers' demand." The quarterly journal of economics 64, no. 2 (1950): 183-207.