首楞嚴義疏注經 8.472

8.472

即前慢習為因也。慢以凌人傲物，高舉自強。洎報鬼倫，遇氣為質，內無實德，空腹高心，飢餓所困，故名餓鬼。

This is caused by the previously mentioned habit of conceit. Conceit insults others and shows contempt for things, exalting oneself and striving to be forceful. When receiving retribution in the ghost realm, they encounter vapor to form their substance; internally devoid of real virtue, with an empty stomach and an arrogant mind, they are afflicted by starvation, and are therefore called hungry ghosts.