Jump On The Bandwagon
A phrase commonly used when someone supports another place/thing for the sole reason that it is popular now, and not that they supported said thing before it spiked in popularity.
Example:
Person A: Look at this prick, last year he was all McLaren and now he's supporting Red Bull because Verstappen won!
Person B: Way to Jump On The Bandwagon, I bet $20 he switches teams if Mercedes win
Person A: Look at this prick, last year he was all McLaren and now he's supporting Red Bull because Verstappen won!
Person B: Way to Jump On The Bandwagon, I bet $20 he switches teams if Mercedes win