My Buddhist Monk friend says the concept of self-hatred isn't a thing in his homeland in SE Asia. Is self hatred a societal trait?

If you mean to say that it is brought about by society, the answer is yes and no.

"Self-hatred" comes from comparing yourself to those around you using societal criteria. For example, girls are taught that being "fat" is bad. If a girl is "fat," she might feel bad that she doesn't look the way that society says she should look, in order to be "beautiful" or "sexy." She will blame herself or her genetics for her appearance, and might eventually come to "hate" herself for it.

This is just one example, but they usually follow a similar pattern.

Self-hate is a free offshoot from original sin. Thanks Jesus

Your friend isn't being truthful. Self hatred is a world problem!