Answer:
Ben most likely has acrophobia.
Explanation:
Acrophobia is a word of greek origin. Derives from Acros, which means "summit", and phobos, which means fear.
Acrophobia is thus, the fear of heights. These can be a serious medical issue in certain situations, as for example, in the scenario described in the question in which acrophobia is affecting Ben so much that he quit his job.