Put in $10,000 once, add nothing, earn 7% a year. After ten years it's $19,672; after forty, $149,745. Each decade roughly doubles the pile, which is why the last ten years add more than the first thirty together.
See all forty yearsThe rule of 72
Every ten years, it doubles.
The 4% rule, tested on 59 start years.
Ten years of waiting costs $651,000.
In year 11, your money starts out-earning you.