At a certain point of wealth inequality under capitalism it becomes more efficient to make everyone else poorer than to acquire more wealth.

Let me try to rephrase this, so that maybe it makes sense. The point I'm trying to make is that social-darwinism is not an extension of capitalism, they're two different things but with aesthetic overlap.

Capitalism aims to optimize work, by naturally rejecting inefficient ways to do things. The production line wins over the workshop. It's about things and processes, not about people directly.

Social-darwinism is about rejecting people. To refuse people the space to thrive or reproduce. To push them to the edge of society until they die from exposure or suicide or simply that their bloodline ends when they can't support their families over the course of generations. Thus the noble classes dominate by right, and whoever is unsuccessful deserves to die and rot.

Except capitalists install Trump, who destroys wealth both for himself and for others. And they put incompetent nepo babies in positions of power where they waste multiple percent of profit. And they give golden parachutes to incompetent CEOs they hired. And they fire personnel only to replace them with consultants that are many times more expensive. And they run their own businesses rather than putting their money in an index fund for hired investors to play with. And they give millions to charities (derogatory) that have no realistic return on investment.

Capitalists burn wealth constantly. Wealth accumulation is not the goal of capitalism, it's the score counter of a game they're playing for the sake of the game, and they will pay anything to keep playing.