Black and white conservatives try to use the 'hard working black immigrants doing better than FBAs' argument to counter black accusations of systemic racism.
There are a few counters to that (among them are America only lets in black immigrants who can be viable economically). Anyway, I think even Thomas Sowell points this out in one of his books, is that the income levels of Black immigrants go down over generations and are equal to Blacks (FBAs) generally. There is no evidence of generational wealth increasing in immigrant Black families. By the 3rd generation they are indistinguishable, statistically than any other blacks.
Those Nigerians bragging about education income levels statistically will not continue to go up by the 3rd generation. It's been that way in black history. The immigrants do well, the 2nd generation does well but the 3rd generation are fully born and raised in America and are culturally black American and suffer the same issues.
You might be able to find an example or two of 3 generations of a black family who were immigrants and passed down generational wealth or success (Colin Powell for example) but its not the norm. Harry Belafonte's children and grandchildren are no where near as successful as he is and although not broke, they aren't nearly as rich and he was very famous. And they started off with a lot money and a famous family member, far more advantages than even the average middle class white person. The family wealth DECREASES over time. If they owned a store, the store doesn't last to the grandchildren. Unlike the Italians for example.
Also, black immigrants, with each passing generation, marries into FBA or other non FBA communities (Nipsey Hussle). Someone is half Jamaican, half FBA, or half Nigerian, half Ghanaian, but both are culturally American. Not sure about the percentages anymore, but at once time an estimated 25% of all blacks in Brooklyn had at least one ancestor who was from the Caribbean. Similarly to Long Island communities like Uniondale or Hempstead.
The one community of generational wealth are the creoles / boule` of Louisiana, primarily New Orleans and to a lesser extent in Baton Rouge and they are FBA.