It’s the nature of the Immigrant, no matter where they go to “establish” themselves. No matter their Race.
If you looks at Blacks from the US who move and live abroad they are more educated, affluent, driven, (social) mobile, than the “natives.”
Just look at the Black American immigrant populations in China, Ghana, Japan, the UK, etc.
Some are aided by the government, some are not, it depends on which group you are referring to.
Also, calling these populations “overnight millionaires” is a broad oversimplification and misrepresentation.
The US government and culture has always used the “success” of immigrant populations to both shame Blacks in the US, and to promote the fallacy that the US is a land of opportunity for anyone who’s willing to work hard.
If you have bought into this propaganda, then I don’t have time or space to dismantle your indoctrination, you can better educate yourself on US and immigration history, or continue to hold to the Racist stereotypes about Black people in the US and US immigrants.