The compound interest effect

🧭 Background & Context The compound interest effect describes the exponential growth of capital when earned interest is added to the original investment amount and subsequently earns interest itself. From an economic perspective, this creates a snowball system of positive feedback: the longer the investment horizon and the higher the return, the more the compound interest portion exceeds the original contributions. For private investors, this effect is the central foundation of long-term wealth building, as it generates considerable sums over decades even with small regular savings amounts. The decisive factor here is time, not the size of the one-time amount – starting early has a stronger impact than any later additional payment. Those who ignore compound interest potentially give away half of their possible final wealth, which is why it is considered the „eighth wonder of the world.“ At the same time, it carries risks: with negative interest rates or inflation, it works in reverse as a wealth destroyer, requiring active management through broad diversification and low-cost index funds. 🔍 How It Works in Detail The compound interest effect means that you not only earn interest on your original money, but also on the interest you have already earned. Imagine you invest 100 euros and earn 5 percent interest – after one year, you have 105 euros. In the second year, you then earn 5 percent on those 105 euros, which is 5.25 euros, and your balance grows to 110.25 euros. This way, your money doesn’t grow evenly but increasingly faster, because each new interest amount itself generates more interest. The longer you leave the money invested, the stronger this snowball effect becomes – it seems slow at first, but after many years, the sum virtually explodes. The trick, therefore, is to start early and never withdraw the interest, but instead let it keep wor …