system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do people go bald on their heads, but not their faces?

Every bald person has a beard....why does the face not go bald as well?
gpt
Baldness, if we're talking the typical male-pattern-baldness you seem to be addressing here and not fringe/rare cases, is caused by the hair follicles found on the scalp reacting to androgens in the body. 

Other body hair does not have this reactivity to the particular androgen, dihydrotestosterone (DHT), that the scalp follicles do... which is why you see completely bald men who have huge beards, hairy arms, hairy chests, etc. None of their non-scalp hair is in danger of falling out because of sensitivity to androgens.