If you start with $100k and compound at 20%, you'll be a bil...

If you start with $100k and compound at 20%, you'll be a billionaire in a mere 50 years. How many investors working class investors from the 70s are billionaires today? For perspective, at 8% someone would've had to invest $100k in 1900 to be a billionaire by now.

I think that illustrates how reasonable of an expectation 20% it is.