No matter if it's the ways of Taishu and Taiji, or the Taixuan World, diligently cultivating through breath control, refining pure Dao essence, tempering the muscles and bones, and solidifying the Dao foundation are all part of the stable and proper path of cultivation.
But while the proper path is stable, it's slow. And directly taking someone else's carefully cultivated magical treasures, nurtured materials, and constructed Dao bodies to use for oneself, that's the way of the demons.
The immortals of the Taiji Realm vie for opportunities and fight over heaven-sent treasures. The demons of the Taishu path are even more straightforward, swallowing their prey whole and assimilating completely—that's the way of the demons, too. The difference between the righteous and demon paths lies in their actions, not in their appearance; this is Li Fan's own understanding.
Of course, he had to admit that the way of the demons was indeed faster.