Slaves or immigrants?

Ben Carson the black, African -american, new secretary of the Department of Housing and Urban Development has compared slaves with immigrants attracting widespread criticism from the usual suspects, the luvvie liberal left and civil rights groups who called his remarks offensive. But hasn't he got a point.
Those originally taken from West Africa for slavery were taken under duress, forced to endure miserable conditions whilst being chained and brutally treated. They were forced to work for long arduous hours on minimum or no pay and denied any sort of freedom for hundreds of years. Yet, some of those slaves may have been pleased to leave the hopeless, disease ridden life of the native mud hut African economy and inter tribal feuding to seek a better life (or die). And is this not the case today?
African immigrants cannot rely on European slave traders to take them, they have to arrange their own version of escape, risking many life threatening perils to find a better life (or die) away from the squalor of the African and Middle Eastern hell holes. Only this time the liberal elite cannot blame rich European landowners of a crime. This time the diaspora of people moving to the green fields of northern Europe and the US are the people themselves. In the days of slavery, the migrants had no choice but is it not the case that because of what happened they DID forge for their descendants the better life they hoped for and that without slavery many African Americans like Ben Carson would not be living a relatively good life compared with their relatives in Benin and elsewhere. You could make a case for saying that many African Americans should jolly well be grateful for slavery.