Why are some idols made fun of in their groups?

Mingyu, Jimin in the early bts days, sunoo, like u catch my vibe right?

What makes them the butt of jokes?

Easy targets

Seventeen said they tease Mingyu because he handles it well and doesn't take it personally. He also likes the attention that comes with being the focus and they do it on purpose if he's not getting screen time lmao you'll notice Mingyu even sets himself up to be made fun of. Making fun of him makes for some pretty funny moments which is why they tend to choose him

Members like Seungkwan and Dino also become the joke target for similar reasons (though they all have their different ways of handling it and are less passive than Mingyu). None of the members in general are safe and they all frequently make fun of each other. None of it is done out of actual malice and you'll also notice them check up on each other in the background sometimes if they're worried a joke went too far.

My guess is the majority of groups do this just for that reason: it's funny and they take it well. People forget idols film things with intent to be entertaining and having "the butt of the joke" is prevalent throughout most comedy forms. Maybe sometimes it goes too far (like one of the examples from OP) and it's up to them to sort it out just like any group of people would irl

Mean members

Quote from Bang Bang Bang (431)

Easy targets

What makes them so

Quote from OP

What makes them so

I noticed the ones who are usually the butt of the jokes are usually the passive members like Yeji, Lisa, Seulgi etc idk about Bgs

Their habit of bullying when they are all still in school, now got carried over.

It's male social group dynamics, similar thing the world over.

In every male social group theres always one thats the "butt of the jokes".

This can be sinister and bullying or it can be good natured and friendly, depending on the dynamics of the group.

It's not Sunoo. It's Jay.

Have you ever seen teenage boys socialize?

Yeah.

For some reason guys seem to enjoy joking about each other as a means to get closer. So most of the time it's not malicious.