Money makes money. Then it makes more money from the money it already made.
A working family usually can’t play that game. Most of its income goes quickly back into the economy—to housing, food, transportation, insurance, health care and education. There may be a little left for retirement or an emergency fund, but not much to compound.
A billionaire can spend extravagantly and still leave nearly everything invested.
This matters for more than fairness. An economy needs people who can afford to buy what it produces, educate their children, start businesses, move for better work and survive a setback without being ruined. When too many families lose that ability, the economy wastes talent and weakens its own market.
OECD research has found that rising inequality can reduce later economic growth, particularly when lower-income households fall farther behind and become less able to invest in education and opportunity.³ Extreme concentration also converts economic power into political power. The people benefiting most from the system gain greater ability to preserve it.
History doesn’t offer a simple formula in which inequality reaches a certain level and civilization collapses on Tuesday. Rome didn’t fall because a few senators got rich. France didn’t erupt in revolution because of one bad tax law. Civilizations come apart through combinations of war, debt, corruption, weak government, social division and lost public trust.
But extreme inequality makes those pressures harder to survive. Wealth concentrates. Elites gain the power to protect it. Ordinary people begin to believe the system no longer belongs to them. Reform becomes harder until a crisis forces changes that might have been made peacefully much earlier.
Recent scholarship comparing the Roman and Han empires found both to have been highly unequal societies in which elites extracted large shares of total income. The research doesn’t claim that inequality alone caused either empire to fail. It does reinforce a more modest warning: societies become more fragile when wealth and power become heavily concentrated and ordinary people lose their stake in the system.⁴
Inequality doesn’t bring down a civilization by itself. It weakens the beams before the storm arrives.
Americans have historically tolerated large differences in wealth because we believed the ladder was still there. Some people would become enormously rich, but work, ability and a little luck could move almost anyone upward.
That belief becomes harder to sustain when the decisive question is no longer what you can accomplish, but what your parents already own.
Our tax system does surprisingly little to interrupt this process because it sees income from work much more clearly than gains produced by ownership.
America runs on two economic clocks.
The paycheck clock is immediate. A teacher, carpenter, physician or television producer earns money. The income is reported, taxes are withheld and the bills arrive.
The ownership clock can wait. Someone earning $10 million or $50 million in taxable compensation reports it and pays income tax. But someone whose stock rises by $5 billion may gain far more wealth, control and borrowing power without reporting that $5 billion as taxable income.
The owner can hold the stock, allow it to compound and borrow against it rather than sell. At the level of a great fortune, those loans can finance an extraordinarily expensive life while the underlying gains remain outside the income-tax system. If the assets are held until death, inherited property generally receives a new tax basis tied to its current value, allowing much of the appreciation during the owner’s lifetime to disappear from the capital-gains tax base.
The issue isn’t that wealthy Americans pay no taxes. Many pay a great deal.