This is a presumed goal/value. A more conservative take is that the rules are actively enforced based on values or justice.
A value could be that we do not support ill gotten gains, to the extent that the majority votes for free things paid for by the minority it could "benefit the majority" and still violate the value
I've actually gone through the rolodex of all known moral systems and none of them endorse the conception that a minority, who just earned it rightfully, is allowed to accrue outsize resources while other groups do not.
So, again; as I said earlier, I open the floor for discussion. This is the moral certainty that the process by which we adjudicate the social order will not be favorable to an unjust conception. The simple light of day ends most of these discussions.
You are entering into a circular argument:
> My whole point is that to the extent accumulated wealth is happening by playing by the rules, there is no injustice in accumulating wealth, nor in accumulating more than those who did not do the actions which relate to wealth building
Ill gotten gains would need to be defined as "not playing by the rules" but you already prescribed that the rules supersede that so there's no way to potentially redefine that such accumulation was ill gotten. Your argumentation makes us stuck in the status quo which is visibly not working for the benefit of the majority, which is objectively true by inspecting the discrepancies between the increase of productivity vs increase of wealth between different cohorts of society.
Isn't an ill gotten gain to extract a disproportionate amount from the gains of productivity? One can still be filthy rich in a society that distributed it more evenly, not equally but at least more evenly. In Western societies this distribution has been severely skewed to the top in the past 40 years, why is that the people labouring with increased productivity do not see the fruits from it? Isn't that an injustice, unfairness, etc.?