Personal wealth is a hot topic every election season, and it raises a good question: how do the rich really get richer? Are they smarter than everyone else, or just luckier? Intelligence and luck play a part, but two other factors matter more for ordinary people: discipline and the power of compounding.
The 401(k) lesson
Retirement accounts such as a 401(k) in the US work quietly in the background. Money comes out of every paycheck before you can spend it, it is invested in funds, and the returns are reinvested again and again. Many people never check the account, yet it ends up as the largest part of their savings. Charlie Munger of Berkshire Hathaway is often quoted as saying that the first $100,000 is the hardest; after that, compounding starts doing serious work for you.
A retirement account locks the money away until old age. The plan below takes the same idea, regular saving plus compounding, and applies it to an ordinary investment account you could access if you really needed to.
What you need
- A source of steady income, even a small part-time one.
- A fixed amount you can set aside every pay period and live without.
- A low-cost investment account, such as a broad index fund.
- A lot of discipline.
The idea is to check the account once every month or two to rebalance, not every day.
Three phases of saving
Younger savers can afford to invest more aggressively, mostly in shares rather than bonds, because they have decades to recover from a bad year. Later in life, a growing share of safer bonds protects what has been built. The figures below assume shares return around 10 percent a year, roughly the long-run average of the US stock market including dividends, before inflation.
| Phase | What you do | Approximate result |
|---|---|---|
| Student (18 to 30) | Start with $1,000 and add $150 every two weeks (about $10 a day) | About $90,000 by age 30 |
| Young professional (30 to 40) | Even if a weak market leaves you with $50,000, add $300 every two weeks | About $260,000 by age 40 |
| Long haul (40 to 70) | Leave around $250,000 invested at a blended return of about 9 percent, and keep adding | Roughly $3.3 million from the lump sum alone, more with continued saving |
The numbers are illustrations, not promises. Markets have bad decades as well as good ones, and inflation means a million dollars in 40 years will buy far less than it does today. But the shape of the curve is the point: most of the growth comes at the end, and it only arrives if you start early and keep going.
The $1 experiment
Start with $1 today, add $1 every two weeks and let it grow at 10 percent a year. After 30 years you will have deposited $781 and own about $4,500. Most of that money is returns earned on earlier returns.
Update (October 2026): This post first ran in 2012, when the annual 401(k) employee contribution limit was $17,000. The limit has been raised many times since and is now well over $20,000; check the IRS figure for the current year. Adjusted for inflation, the long-run US stock market return is closer to 6 to 7 percent a year than 10, so treat the table as a best-case illustration. Low-cost index funds and automatic transfers have made the plan easier to follow than it was in 2012.
The casino knows this maths too
Compounding is not just a saver's tool. It is also why casinos are so profitable. A casino game is designed with a small, fixed advantage for the house, often between 1 and 5 percent per bet. On a single bet you can easily win. Over millions of bets, the small edge compounds into a near-certain profit for the house, exactly the way a small annual return compounds into a fortune for a patient investor.
The lesson for a student is simple. Put the law of large numbers on your side: be the investor who collects a small edge thousands of times, not the player who pays one. If you enjoy the odd night at the tables, budget it as entertainment, not as an investment. Our explainer on house edge and expected value walks through the numbers game by game.
Key to financial freedom: save with discipline and let compounding work for as long as possible. Ten dollars a day at 18 is worth more than a hundred dollars a day at 45.