The Twin Experiment
Twins A and B have identical incomes. Twin A invests $200 per month at 7% annual return from age 18 to 28, then stops completely (10 years, $24,000 total). Twin B starts at 28 and invests $200 per month at 7% until age 60 (32 years, $76,800 total). Who has more at 60?
Twin A: $24,000 Invested → About $289,000
Twin A accumulates about $34,600 by age 28 ($24,000 principal plus $10,600 in returns). Then the money sits untouched for 32 years. $34,600 times (1.07)^32 equals approximately $289,000. Zero additional contributions for 32 years, yet the account grew from $34,600 to $289,000 purely through compounding.
Twin B: $76,800 Invested → About $276,000
Twin B diligently invests $200 every month for 32 years, contributing $76,800 total. At 7% annual return, the account reaches approximately $276,000 by age 60. Despite investing $52,800 more than Twin A, Twin B ends up with about $13,000 less. A wealth building book explains why starting early is the single most powerful financial decision.
Today Is the Youngest You Will Ever Be
Twin A's $24,000 had 42 years to compound. Twin B's $76,800 had at most 32 years. Those 10 extra years of compounding outweighed $52,800 of additional contributions. The lesson is clear: in investing, when you start matters more than how much you invest. You do not need to start investing as a teenager, but knowing that the compound interest clock is always ticking gives you an edge that no amount of money can buy later.