Varför slutade Griphook att arbeta hos Gringotts Bank?

Bäst om goblinerna bara förklarar det själva, som de gör i boken:

There was another pause in which the fire crackled and the river rushed on. Then Ted said, “And where do you two fit in? I, er, had the impression the goblins were for You-Know-Who, on the whole.”

“You had a false impression,” said the higher-voiced of the goblins. “We take no sides. This is a wizards’ war.”

“How come you’re in hiding, then?”

“I deemed it prudent,” said the deeper-voiced goblin. “Having refused what I considered an impertinent request, I could see that my personal safety was in jeopardy.”

“What did they ask you to do?” asked Ted.

“Duties ill-befitting the dignity of my race,” replied the goblin, his voice rougher and less human as he said it. “I am not a house-elf.”

“What about you, Griphook?”

“Similar reasons,” said the higher-voiced goblin. “Gringotts is no longer under the sole control of my race. I recognize no Wizarding master.”
Harry Potter and the Deathly Hallows, Chapter 15 - The Goblin's Revenge

Det verkar tydligt att det Voldemort-kontrollerade ministeriet störde kraftigt med att driva Gringotts, bland annat genom att ge ett antal order till goblinerna som stred mot deras rasliga stolthet och övertygelse.

Han vägrade att acceptera att vara under kontroll av trollkarlarna efter att Death Eaters tog över ministeriet. Mer finns på Wikia .