With their YouTube channel exceeding 70 million subscribers, BTS have now surpassed Justin Bieber to become the second-most subscribed artist on the streaming platform. The seven-piece South Korean boy band, made up of Jin, Suga, J-Hope, RM, Jimin, V and Jungkook – are ahead of Justin Bieber, who has 69.7 million subscribers. BTS’ six videos,…