I think it does matter. Almost every discussion of inequality seems to be tied to a discussion of whether to use taxation (or other laws) to change it, with a view to changing these other things. And that only works if the causal link is from the money to the bad things.

I'm not sure that there is no causality, BTW. I'm just objecting that too much discussion assumes it's obviously all causality: The money just falls from heaven onto certain Brazilians, not others, and that's why Rio has the murder rate they do, and you could fix it with income tax. This seems crazy.