Time – the most powerful wealth-building tool

Most people understand the concept of interest. Far fewer appreciate the incredible impact of compound interest, which is simply earning returns on both your original investment and the returns that have already accumulated.

Over long periods, the effect can be amazing. Albert Einstein is often credited with saying compound interest is the eighth wonder of the world. Regardless of whether he actually said it or not, the principle remains true and underappreciated.

Compound interest allows wealth to grow exponentially rather than linearly – which means the growth accelerates as the wealth grows instead of just increasing at a constant rate.

Many South Africans underestimate how powerful this can be because the benefits are not very exciting in the early years. Wealth creation through compounding is often slow, boring, and almost invisible at first. The magic only reveals itself after decades of consistency.
 

A simple example of compounding

Consider someone earning R20 000 per month who decides to save 15 percent of their income. This equals a monthly investment of R3 000.

Let us assume they invest this money in a diversified growth portfolio and earn an average return of 10 percent per year over the long term. While markets rarely deliver smooth annual returns, this assumption provides a useful illustration.

After 10 years

• Total contributions: R360 000
• Investment value: Approximately R615 000

Already, their investment growth has added more than R250 000 to the amount they personally contributed.

After 20 years

• Total contributions: R720 000
• Investment value: Approximately R2.3 million

Notice what has happened. Contributions have doubled, but the investment value has almost quadrupled.

After 30 years

• Total contributions: R1.08 million
• Investment value: Approximately R6.8 million

At this point, the investor has contributed just over R1 million of their own money, while their wealth has grown by over six times that amount.

After 40 years

• Total contributions: R1.44 million
• Investment value: Approximately R19 million

Now we can see the true power of compounding become evident. The investor's own contributions account for less than 10 percent of the final portfolio value. The rest comes from investment growth compounding over time.

Saving your first million is the hardest

One of the intriguing aspects of compounding is that the journey accelerates as time passes. The first R1 million of wealth can take many years to accumulate because the portfolio is small and investment growth is modest. However, once a larger capital base has been established, growth begins to work much harder.

A portfolio worth R100 000 earning 10 percent generates R10 000 of growth in a year.

A portfolio worth R5 million earning the same 10 percent generates R500 000.

The return percentage is identical, but the Rand value created becomes much larger because the capital base has expanded. This is why long-term investors often feel as though "nothing is happening" for the first decade, only to see substantial growth in later years.

Time matters more than the amount you invest

Many people delay investing because they believe they need a higher income first. While increasing savings is important, time is often the more valuable asset.

Let us consider two investors:

• Sam starts saving R3 000 per month at age 25.
• Sam’s Bestie waits until age 35 but then saves twice as much, R6 000 per month.

Sam’s Bestie contributes significantly more capital over their lifetime, yet Sam will often accumulate similar or even greater wealth because those early contributions enjoyed an additional decade of compounding. Starting early is usually more important than starting big.

The real challenge is staying invested

Understanding compound interest is easy but benefiting from it is far harder. Long-term investors must endure market downturns, economic recessions, political uncertainty and periods when investing feels pointless. The temptation to stop contributions or move to cash can be overwhelming.

However, compounding requires two key ingredients:

1. Regular contributions.
2. Time.

If one interrupts either ingredient the outcome will change dramatically. The most successful investors are often not those who select the perfect fund or accurately predict market movements. They are rather the individuals who consistently save, remain invested, and allow time to do the heavy lifting.

The big takeaway

For many South Africans, financial freedom is not built through winning investments, inheritance, or extraordinary income. It is built through the discipline of investing regularly and allowing compound growth to work over decades.

A person earning R20 000 a month who consistently saves 15 percent and remains invested for 40 years could build a portfolio worth many millions of rand, despite contributing less than R1.5 million themselves.

The most important decision is therefore not which investment to choose tomorrow. It is deciding to start today because when it comes to compound interest, the one thing you can never recover is time.