To summarize the value of the Infinite Growth Set in one sentence:

In the century-long history of the Otherworld's descent upon Earth, there has been only one set worldwide, which is the Extraordinary Set on Zhang Yue!

As the world's top professional powerhouse, Ghost Swordsman Alpha has slain several King-level BOSSes.

Yet even a level 500 King-level BOSS does not have the potential to drop an Infinite Growth Set, at most it might drop a single piece of Infinite Growth equipment.