What he "means" to the extent this isn't just a shock value post meant to allow him to get a lot of responses before moving the goalposts & also to get a lot of nazis to like him more, is that:

1. The epithet he used is a racist one used to describe how people (usually black people, but not exclusively) who come from a poor background act once they get some money - often on flashy displays of wealth, but not often on investments/ensuring their wealth grows and lasts into the future. Not that this is actually true, but that's the idea.

2. he is saying American billionaires fit that epithet because of how they spend their money. He calls them N*s because of how they spend money, not because they are black - he is not under the illusion that most billionaires are black.

3. he's saying they spend their money in foolish ways. He would prefer they spend their money abolishing the neoliberal state and replacing it with a neo-feudal monarchical system that makes all these billionaires literal feudal lords with fiefdoms. For him, this is the end-goal of wealth and the ideal societal state.

4. also, he thinks that he is an intellectual and that his tweet is a serious philosophical argument.