Compound Interest

Compound interest is growth on growth: your principal earns a return, and that return then earns returns of its own. Simple interest on $100,000 at 5% pays $5,000 every year forever; compounded, year two pays on $105,000, year three on $110,250, and by year 30 the balance is $432,000 — more than four times the simple-interest outcome. The curve starts flat and ends vertical, which is why the last decade of a compounding plan produces more growth than the first two combined.

Three variables drive it — rate, time, and continuity — and continuity is the one everyone underrates. Every interruption (a withdrawal, a liquidation, a "pause") doesn't just cost the dollars removed; it kills every future dollar those dollars would have generated. A $30,000 withdrawal at 40 isn't $30,000 — at 5% compounding to age 70, it's roughly $130,000 of retirement wealth. That invisible cost has a name: Opportunity Cost.

The force runs both directions. Credit card balances compound against you monthly at 20%+; the same exponential math that builds a fortune in your favor digs a crater when the bank is the beneficiary. Which side of compounding your household sits on — net earner or net payer of interest — is arguably the single most important fact in its financial life.

This is why uninterrupted compounding is the design goal of Infinite Banking. Cash Value in a Whole Life Insurance policy compounds on guarantees plus dividends, and a Policy Loan lets you use capital without interrupting the curve — the collateral keeps compounding while the borrowed money works elsewhere. Contrast that with "pay cash and interrupt" or "finance and pay the bank's compounding": the third option — collateralize and keep compounding — is the whole point.

Einstein probably never called it the eighth wonder of the world, but the misattribution survives because the math deserves the title. Start early, stay continuous, and be the one collecting it.