Huatian Palace could accumulate so much wealth and make those sects from the Inner worlds - who had saved up their wealth with much difficulty - give their wealth to the palace because only Huatian Palace had treasures from the various immortal cultivation worlds. Of all the immortal cultivation treasures of the Source world, 70 percent were from Huatian Palace.
Warrior sects could not make pills, treasures, Stratagem Destroying Flags, or talismans… All the treasures that they needed could only be bought through the Huatian Palace. Even if they were to pay a price that was several times more than what the item was worth, or even more than ten times the worth of the item, they were still willing to do so. This was because having materials for immortal cultivation such as spiritual medicine and mineral stones was as good as having trash to them. No matter how much they had, they could not make use of them. What was the point?