Bandwagon Effect (Why do people support opinions when they become popular?)
The Bandwagon Effect, a brief explanation
What is the Bandwagon Effect?
The bandwagon effect describes the tendency to support a viewpoint that is popular.

Examples
In politics when voting if there is a major publics opinion in favour or against something then a voter may go with this opinion when making a choice.
In sports the bandwagon effect can be seen when an increasing number of people support a sports team after they have had some success despite having very little success before.
The literature
Bindra, S., Sharma, D., Parameswar, N., Dhir, S. & Paul, J. (2022). Bandwagon effect revisited: a systematic review to develop future research agenda. Journal of Business Research, 143, 305-317. Doi: 10.1016/j.jbusres.2022.01.085
Farjam, M. (2021). The bandwagon effect in an online voting experiment with real political organizations. International Journal of Public Opinion Research, 33(2), 412-421. Doi: 10.1093/ijpor/edaa008