My 9-year old niece is a fanatic of a local loveteam. She watches their noontime show daily and begs her parents to buy their magazines, albums, and even the products that they endorse. Should we tolerate this behavior?

There's nothing wrong in supporting what they like, as long as it won't take too much of their time away from more important things like studying. My parents were supportive of my F4 fangiriling phase and I would love to pay it forward to other kids as well. It's a fun phase :)