Albert Einstein reportedly said: Compound interest is the eighth wonder of the world. He who understands it, earns it. He who does not, pays it. Whether Einstein actually said this is debated — but the statement is correct.

What Is Compound Interest?

Compound interest means: You earn interest on your interest. In year one, you earn interest on your capital. In year two, on capital plus year one interest. In year three, on everything combined. The effect is exponential — and becomes more powerful the longer you stay invested.

The Power of Time: Calculations

Example 1: 10,000 Euros at 8% p.a.

After 10 years: 21,589 euros (+116%)
After 20 years: 46,610 euros (+366%)
After 30 years: 100,627 euros (+906%)
After 40 years: 217,245 euros (+2,072%)

Note: In the first 10 years you earned 11,589 euros. In the last 10 years (year 30-40) you earned 116,618 euros — ten times more. The magic happens late.

Example 2: 300 Euro Monthly Savings at 8%

After 10 years: 54,914 euros (invested: 36,000)
After 20 years: 176,488 euros (invested: 72,000)
After 30 years: 447,107 euros (invested: 108,000)
After 40 years: 1,054,823 euros (invested: 144,000)

300 euros monthly becomes over 1 million euros. Not through genius stock picking, not through market timing — only through time and consistency.

The Rule of 72

Simple rule of thumb: 72 divided by interest rate = years until doubling.

At 6%: 72/6 = 12 years
At 8%: 72/8 = 9 years
At 10%: 72/10 = 7.2 years
At 12%: 72/12 = 6 years

The Greatest Enemy of Compound Interest

Starting too late: 10 years later costs half the final wealth
Interruptions: Panic selling loses the most valuable recovery days
High costs: 1% higher costs per year reduces final wealth by 25% after 30 years

Compound Interest + AI Trading

If your AI-managed portfolio delivers 12% instead of 8% p.a., the compound difference is massive:

300 euros/month, 30 years at 8%: 447,107 euros
300 euros/month, 30 years at 12%: 1,048,489 euros
Difference: +601,382 euros — solely through 4% higher return from AI

Bottom Line: Compound interest is the most powerful force in wealth building. It requires no genius, no luck, and no large starting capital. It only needs one thing: time. Start today.