Far more probability estimates are wrong on the over-optimistic side than the under-optimistic side. Youll rarely read about an investor who aimed for 25% annual return rates who subsequently earned 40% over a long period of time. You can throw a dart at the Wall Street Journal and hit the names of lots of investors who aim for 25% per annum with each investment and end up closer to 10%.

The Great Mental Models by Shane Parrish