That's news to the ALDI brothers and Henry Ford. Capitalism used to be about the exact opposite. We moved from low volume - high margin, extractive feudal-like economics to consumer capitalism, high volume low margin. You create wealth by churning out commodities at low margins that the average worker could buy.
The tech industry is trying to exactly reverse this, as Varoufakis appropriately points out, by returning to techno-feudalism where you're not a consumer but a sort of platform serf. High volume commodity markets is exactly what these people try to eliminate to return to a kind of direct resource extraction.
Look, I am not saying there aren't horrible flaws with capitalism. There are a ton, and we should, as a society, work to mitigate them.
I just don't think the solution to the problem is for us to ask capitalists to not seek the highest margin. This is not a problem that is fixed by people just being more moral.
We fix this problem through public policy.