Question: Is there an in-universe explanation as to why the Ancient One is bald?
In other words: what caused her to go bald? (I’m after an in-universe answer, i.e. not “the director”). When a woman goes bald, it’s generally for a reason, e.g. she has an illness that makes her hair fall out. (This is unlike a man.)
Perhaps she stopped growing hair for some reason (although she still has eyebrows), e.g., because she's very old (ancient, in fact). Or perhaps she shaves her head each day. Or maybe she uses her magic to get rid of hair. I have no idea.