"Wealth, as Mr Hobbes says, is power." --Adam Smith.
One person cannot hoard all the sex appeal, or charisma, or attractiveness, or health, or intelligence, or age. These are all ultimately bounded. And except in a very general sense, they are not heritable, most certainly not in a cumulative sense as with financial wealth.
Physical possessions and relationships are similarly bounded. One person might have far more grain, or friends, or lovers than another, but the upper-bound limits are still relatively low, the aquisition and carrying costs are high, and most of such things provide little by way of direct power of and by themselves.
Money and wealth are intrinsically unbounded. They also tend to compound. Matthew 25:29: "For unto every one that hath shall be given, and he shall have abundance: but from him that hath not shall be taken away even that which he hath." Modern experience tends to bear this out: those who start with an advantage tend to do better than those who do not.
In a world with boundless accumulation, the accumulation of power leads to a monopoly on power. The individual or company which has the most wealth within a town, or city, or state, or country can determine who works and who doesn't, who can buy or rent a home and who cannot, who can open their own business or not, who can receive loans, etc. At sufficient levels, wealth funds education, research, and disciplines (the field of economics is rife with this, through to the current day as with the wholesale funding and direction of economics departments, faculty selection, and curriculum at the University of Florida.[1] Note that Smith himself lived largely on patronage from nobles.
Aspects of economics also distinguish between income based on direct work (wages) and trade (sale of commodities or high-ticket goods), and of the unearned income of economic rents (as in land rents, returns to capital, interest, or awards to some specific monopoly, large or small). Labour is directly rewarded according to the the value produced at market prices with the surplus value going to the purchaser. Rents include the surplus value based on scarcity and an inelastic supply, providing the propertyholder an unearned income above costs.
(Smith makes clear that the fundamental price of a product should be the cost it takes to produce, most especially in labour cost. This pressages Marx's Labour Theory of Value, though also the Marginalist notion of marginal cost of production.)
Market failures of unpriced externalities, both negative and positive, also result in inefficient pricing, as do the effects of greater or lesser market power through superior coordination, control, information, or generally a superior Best Alternative to Negotiated Agreement (BATNA), detailed by Smith especially in labour-employer relations (much discussed elsewhere in this thread).
With inheritance, all connection between work and reward, supposedly the heart of a market-based economic system, is lost, as heirs inherit the wealth of ancestors without having actually worked for their advantage.
The ultimate consequence of an ever-compounding inequality is ultimately that of the "Utility Monster" or "Freedom Monster", in which a single entity has all the money, utility, or freedom within a system, and all the other players have, collectively, none.
http://existentialcomics.com/comic/259
In practice, revolutions (or foreign invasions of a greatly weakened nation) tend to be the limiting factor on such developments.
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Notes:
1. https://publicintegrity.org/politics/koch-foundation-proposa...