A Little Inside, But Too Easy To Pass Up...

bandwagon
noun

Idiom: jump on the bandwagon (climb on the bandwagon)

To join, or show interest in, an activity or movement that is fashionable or likely to succeed and in which one previously had no interest, especially to do so for the sake of personal gain or to improve one's public image.
Etymology: 19c: the bandwagon was originally the wagon or lorry at the head of a parade, on which the band played.