Sort of. Less cynically, the economy is not a zero sum game so some of those returns can be organic shares of positive-sum activities that make life better for everyone. Cynically, they sure don't have to be, because peasant juice tastes just as sweet. There is an awful lot of runaway rent seeking hiding in the clothes of "investment." Either way, assets represent an entitlement to the proceeds.

My point here isn't so much to pass moral judgement on capitalism as it is to assert that money and assets have fundamentally different character. They are easy to confuse due to the liquid market for exchanging the two, but the lines of reasoning that lead us to a concept of "enough money" do not lead us to a concept of "enough assets." We might independently arrive at a concept of "enough assets" by hypothesizing a situation where one person controls a 10% of world GDP or something but world GDP is 100T and the richest people own about 100B in assets so at a 10x multiple they are probably at least three orders of magnitude removed from a self-serving definition of "enough assets" (and that would be the relevant definition, since they would be the ones defining "enough.")

tl;dr Rich people DO stop maximizing money -- but then they start maximizing power, which can be bought with money, and which we measure in units of money.