Unlike other vampires, Vampire Lords did not need to consume blood to survive. All vampiric beings in the Divine Blood Realm were capable of self-sustaining through the blood energy derived from their divine blood.
Their divine blood was like nuclear furnaces or the sun, capable of producing vast amounts of energy for a long time. However, this was also under the assumption that they didn't lose or deplete it for various reasons.
Otherwise, they would still need to consume blood or other sources of energy to replenish their divine blood.
In particular, blood was a delicacy to them as it could improve their divine blood.
Thus, even though Vampire Lords didn't need blood to survive, most of them still had bottomless desires to consume blood. After all, it could improve their power and satisfy their tastebuds.