It only becomes an obsession if it interferes with your daily life
Let's look at it from this perspective, shall we, and select football as an example. And trust me, this is not a scoff at the game, because I've been a fan since high school.
Do you know anyone who's seriously into the sport? How about that certain someone that decorates their "cave" with memorabilia, and posters, and also wears their team's jerseys at every opportune moment, and attends every home game, religiously? Or how about the person who won't budge from the couch all season because they have to watch every type of football game in existence, including college and pro teams?
So, how is this any different from a person who hangs BTS posters on their walls? To be honest, it isn't. But, could this fandom, or any other behavior, turn into an honest obsession? Sure. I say anything becomes an obsession or addiction when it begins interfering with the flow of your daily life. Are you spending money you don't have, and going into debt? Do you no longer socialize with friends or family? There are many red flags.
I too am part of the BTS fandom. I am ARMY, and I've admitted how much I love the "boys". It's fun for me, and if you've read my other entries in this blog, you'll also realize that they've made my good life even better, for they have inspired me with their message, their music, and their wonderful personalities. Do I think I have a "problem"? No! But I do spot problematic behavior in a few select individuals on Twitter, and I do believe it may be cause for concern. However, the vast majority of people I interact with on social media (and many are wives, moms and grandmoms), are "normal" everyday women, who simply have an avid appreciation of BTS.
And now I'm off to get some work done. I do have another life!