To bring a society from oppressive tribalism into a glorious golden era requires significant funding. When Emperor Valkorion began his project, he funneled wealth from the Sith Empire into Zakuul, effectively robbing one empire to fund another. As Valkorion's grand society blossomed, the Eternal Empire turned its view outward, conquering planets and claiming their resources. By the time the Republic and Sith Empire fell, Zakuul had amassed the greatest fortune in the galaxy.
Much of it is channeled directly into Zakuul–expansion of the Eternal Fleet, lavish updates to the Spire, generous gifts to the citizens–but the Empire's treasure is so great, it couldn't possibly be spent entirely. The bulk now sits idle aboard the massive treasury called the Gilded Star, serving as a symbol of Zakuul's status–and a reminder of the Eternal Empire's power.