It's fascinating how many people this statistic is tripping up. If 80% of roles are taken by white people, the remainig 20% are taken by EVERYBODY else. Not just black people. Also, white people make up around 60% of the population.
Black immigrants (as well as many descendants of slavery, let's be clear), are successful because it is possible to succeed today regardless of your skn colour. I've not denied that, in fact, I'm living proof.
But to lean on the example of the most successful as a model for everybody is deeply flawed logic (see this video for a succinct explanation of why https://twitter.com/bhaviklathia/status/1370386348910198791?s=21), as well as dismissive of the injustices I mention in the article.