Today's world is a winner take all world.
Once a company/act/style takes over, the barriers to enter are too high.
No one will ever beat Microsoft, Apple, Facebook, Alphabet(Google), etc, because the base they have built is too strong and are unassailable.
In K-O-R-E-A, the head start established by Melon is too big for any competition to overcome, and if I go further the discussion will be about a certain singer so I will stop here.
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The rise and fall of Brave Girls shows that late blooming is largely meaningless.
BG , OhMyGirl and other acts which bloomed quite late in their careers never really were able to establish any coherent foreign sales base since the foreign listeners stayed loyal to their existing faves and didn't have room for who were the bottom feeders when their faves were rising high.
Which is why there are a lot of fandom wars among the newer acts, since it is very, very, very important to establish who is superior to whom before the rank gets stuck.
Once it is stuck, it is basically eternal. Things are getting tougher for the late bloomers since all the monies are going to the top acts, even more than before. Once a fanbase is established it is for the duration of the act unless the act does something very very stupid; newer acts find it harder to break into the wall of existing acts of the generation, and , although this is cruel to say, acts which did not go anywhere in their first 24 months of debut are not really going to build a sizable fanbase in the overseas to make it viable for a long term.
tl.dr. There is no 'who laughs the last wins' in KPop. One has to establish one's rank fast or there is no coming back. The fandom knows that very well and becomes very aggressive to make sure their faves establish their rank asap.
