fad wagon
Jumping on the fad wagon is when you see something popular and you think it’s the best thing since sliced bread, even though you’ve never had bread.
He bought a ‘fitness tracker’ just because his friend said it was the future.
She signed up for a ‘yoga challenge’ and now she can’t stand up straight.
My brother got a ‘VR headset’ and now he thinks he’s in a spaceship.