along with new players, older players also returned with the velious release. furthermore, lots of people had been hoarding kronos in anticipation of velious and in anticipation of ever-increasing prices, which inflated the price up to the 8k peak but now that folks need cash for important transactions (gems, armor MQs, spells, etc.) a lot of the same folks liquidated their krono.
honestly i'm not really surprised at the slump. krono went up almost 2kpp over the course of 2 weeks back in february before settling for several weeks at 8k. i sold my first krono at 6k and was kicking myself a week later when they were up at 7k.