What is the seventh wonder of the world?

Compound interest.

If you have very small kids or grandkids, they can benefit from the miracle of compounded interest. Justin Ford, wrote a brilliant book called Seeds of Wealth. It is all about saving just $1 a day for your kids so they have a substantial nest egg by the time they are young adults.
Continued.

According to Justin, “Even if your children average just over $1 a day in savings
through the preteen years and a little more than $2 a day through the age of 21,
they can still end up with anywhere from $335,854 (at a 13.2% return) to $855,279
(at a 18.8% return) a generation from now.”
Young people start saving $150 per month in your 401 or put it in a growth dividend stock that has a drip plan.
With growing dividends and compounded and added systematic savings by the time you or your child are 30 years older you will have accumulated with an average of 15% yield $1,000,000 with only a $54,000 investment.

That's why compound interest is the seventh wonder of the world. It takes discipline and sacrifice but that is how Warren buffet did it. He's had 60 years and if you or your parents did the $150 a month you would have $93,000,000 by now. Amazing.