To be very successful you have to be popular internationally.
Gfriend, Brave girls had #1 songs in Korea and were popular in Korea only, and one has disbanded and the other I would consider struggling now. AOA, OMG, Apink are other examples.
Boy groups in general, even the less successful ones, are popular internationally, and get enough revenue touring, even small venues.
Momoland, laboum, lovelyz, clc... If not for the big companies groups, basicly the whole 3rd Gen got aabandonded in the Last few years.
BB Girls have allways struggled. Rollin sold like 1000 copies. They are an anomaly in Kpop run by the members dedication to their craft.