bandwagon
noun [ C, usually singular ]
uk/ˈbændˌwæɡən/ usan activity, group, etc., that has become successful or fashionable and so attracts many new people:
A similar force is the peer group bandwagon: I may watch a television programme not only because I like it but because I want to be able to converse with my peer group.
jump/climb/get on the bandwagon disapproving
to become involved in an activity that is already successful so that you can get the advantages of it yourself:
The success of the product led many firms to try to jump on the bandwagon.