Flying a supreme-grade flying ship at the speed of an advanced Supreme God naturally consumed a huge number of divine crystals. Very few members of prime supreme-rank forces could afford such extravagance.
In fact, if it were not for the fact that Yun Qing Yan was determined to catch the kidnapper, the two intermediate Supreme Gods would not have easily used their divine crystals in such a manner.
Initially, the old man used his divine crystals. He was confident the other party would soon slow down in fear of exhausting his supply of divine crystals. However, contrary to his expectations, even after he used up all of his divine crystals, the other party showed no signs of slowing down at all. Clearly, the other party possessed more divine crystals than him. In the end, he had no choice but to use the divine crystals Yun Qing Yan brought out earlier.