Having disdain for one's appearance and self is probably influenced by the area and environment in which one grows up and develops in, especially if they are a minority group in that population. However, I am white so please feel free to take this with a grain of salt or tell me to hush if I am overstepping.
If someone is living in an area where certain cultures are dominant and they feel as if they don't fit in with that majority culture, a person can feel influenced to conform to it and try to emulate those norms rather than embracing their own identity which may not align with what they are exposed to in popular culture and media. This is especially prevalent when it comes to appearances, and being unable to live up to the beauty standards of those around you.
One example I can think of is how kpop idols and kdrama actresses set up unrealistic standards of beauty for the youth who idolize and follow them. In south korea plastic surgery and the cosmetic industry are booming because unrealistic expectations of aesthetics are becoming normalised. This is making a lot of Korean youth resent their natural features and attractiveness, because they have been shamed into believing that looking like an idol is the norm. Many idols have undergone extensive cosmetic procedures, harsh diets and training regimes, etc to maintain their looks, and that lifestyle is unhealthy for anyone.
I grew up in an area where there were not very many asians, but my ex boyfriend and his family whom I met as a teenager had immigrated from Japan. I found my ex to be insanely attractive and so did many other women, but he said that he often got snubbed because American women tended to prefer stereotypical rougher, tall muscley white and latino guys, and viewed asian men as less masculine. This blew my mind because I have always been turned off by those sorts of hypermasculine/tough traits and never really fancied any of the men in the culture I grew up around because what I liked in a person was just different from what I was surrounded by. I did not share many of the values as those around me like religion, or love of sports. Also, I look very different from most people where I grew up and was heavily bullied for it.
So I think that there is unfortunately a bias in certain parts of the world that make asian men feel inadequate, and this is deeply unfair. Yet, I've experienced the opposite as well in countries where white people are the minority and it has lead me to believe that such beliefs are a consequence of growing up insular communities where different cultures and ethnicities don't mesh and interact as much and there's very little integration that makes everyone feel welcome, accepted, and for lack of a better word, to feel like they are "normal" amongst their peers.
Being in a more multicultural place for a long time has been very telling. Though, many of the people I've interacted with and become friends with at university are east asian international students, and I have frequently heard many of my friends say that white women are ugly, and even dirty, which shocked me, until I realized they grew up in places that are pretty ethnically homogenous with few foreigners. My ex also made a comment to me once that white people are naturally filthy and it's why we need to wear deodorant while Japanese people don't! This made me incredibly self conscious about my appearance and thinking that there was something wrong with me, even though I know realistically it's a different flavor of the same racist garbage my ex was exposed to when moving to America.
I also stayed in Japan for a fairly long time, and happen to really love Japanese fashion. Which unfortunately, is not very accessible to people of various body types and builds. I am very thin but have a larger bust and waist, and I quickly learned that in Japan it's 1 サイズ only most places, and that my body type was just not the norm there. While most people were extremely friendly, polite, and welcoming, there were several instances of men being creepy towards me or saying crass things towards me and my other female friends because we were foreigners (two of us white and one who is half chinese) even though I only spoke Japanese while there and was extremely quiet, polite, self conscious and trying my best to fit into the culture.
There are a lot of foreigners living in Japan who feel alienated and ugly for not being able to live up to Japanese beauty standards, because they are black, white, indian, malay, etc and the clothes are designed for short and petite japanese women, makeup is made for very light skin, people gawk at you for being a different race, etc. Discrimination against foreigners is unfortunately common and accepted, which I really hate because I love so much about the culture, I love learning the language, speaking to the older people who taught me lots of history, but I completely hated feeling like no matter how much you try to assimilate you will never be accepted if you are a different race and nationality.
After witnessing what I did growing up (seeing a lot of racism and prejudice towards anyone who wasn't white) and then also experiencing the same thing in Japan, I think self hatred is unfortunately a natural consequence of feeling like you don't belong wherever you live, and thus people want to conceal their appearance and their culture to try and fit in more, or wish they could be someone else. I wish we had a more accepting world where people were exposed to different cultures at an early age and could see themselves as beautiful without thinking they need to change who they are to be attractive to others.
