The space of a material universe was not made for carrying the weight of higher dimensional immortals, and the space of Vyraak Dominion had lasted so long in the presence of so many higher dimensional immortals because of the great investment of the Vyraak Dominion in strengthening their universe to hold so many God Kings and lesser immortals, an average universe may hold a dozen God Kings, Vyraak Dominion held millions.
Although they had not brazenly conquered other universes to enrich their own, they had been the dominant force in this area for many Minor Eras, and other universes were basically subservient to them, making it easier for them to harvest the remnants of those universe's Wills when their lifespan came to an end, enriching the Vyraak Dominion.