A bunch of reasons. Me and my parents left mainland China 20 years ago to immigrate to Canada. My younger brother was born in Canada. So we are Western-educated. However, I wouldn’t say I’m “brainwashed” by Western media as Chinese people would say. I’ve visited China on several occasions, and have mainland Chinese friends.
Here’s my problems with most mainland Chinese (not all mainland Chinese because you can’t paint 1.3 billion people with a broad brush)
-they talk/argue too loudly. Mandarin isn’t a language that requires you to talk loud. Taiwanese people for example, speak Mandarin normally. I speak Mandarin normally at normal levels. My parents do as well. You don’t need to shout or argue all the time.
-they are too prideful and nationalistic. see my answer here: Tong Zou’s answer to Is the CCP encouraging the rise of Chinese nationalism?
-they talk down about other Asian countries (Korea, Japan) for no good reason, its as if they were educated and brainwashed to dislike other Asians or something without ever acquainting themselves with those people.
-they show off too much and care too much about money. expensive brands, expensive cars, jewelry, etc. too materialistic. This is ‘face culture’. If you look at all the richest people in the world (Bill Gates, Warren Buffet etc) you will notice one thing they have in common is that they don’t show off. Money is just a means. It’s not something to judge someone on. I mean, I had half a million dollars in net worth last year, but I lost it all this year in that QuadrigaCX cryptocurrency scam (see here: Software Engineer Loses Life Savings in Quadriga Imbroglio) . Will a Chinese person look at me differently now? because I haven’t changed as a person. just my net worth. Then again, this is more of a Western culture thing that you should pursue your happiness rather than money.
-they don’t care about their appearance enough. Ironically, despite spending money on expensive products, they actually don’t know how to dress well, or match clothing. Chinese women will wear those dorky glasses even knowing that they look much better without them, or go outside without makeup, it’s as if they give zero F’s about what they look like. Sometimes I think they dress ugly on purpose or something.
-they don’t care about others. I’ve noticed this whenever I go to China. It’s everybody out for themselves. People are not as closely tight knit as they are in Korea/Japan. It’s hard to trust people in China.
These are not only my thoughts but also my parents as well, as they generally agree with what I’ve mentioned so far.