A lot of people moving to core due to several things, i will list some points that i see. This way maybe the staff here know why their profit is reducing...
Common points i see ppl going to core:
No god jewels / god cloaks/god agathions, that makes a little bit more competitive game
Prices: A lot of itens are cheaper there, like dragon weapon, jewels, dragon accessories, artifacts. Everything from the "L2store" is cheaper.
Prestige pack / Premium Account: In core you can buy 6 months the premium account same as prestige pack for chronos and u get a disco