China still has huge wealth disparity. So, while China might seem overall more prosperous than Argentina, Chinese emigrants are often from parts of the country with a standard of living below Argentina's.
And there are other reasons to move too, like air quality, a pressure cooker educational system, extremely high housing cost as a multiple of salary...
Sure, but there's plenty of starving people in Argentina as well, not all the country is as wealthy as Buenos Aires. So the question is, why do they come here instead of going to a bigger chinese city? My guess is that they already have a support network here. That's why many of them end up working in the same businesses, such as running small supermarkets.
https://amp.cnn.com/cnn/2016/05/27/europe/china-children-edu...
And there are other reasons to move too, like air quality, a pressure cooker educational system, extremely high housing cost as a multiple of salary...