"Acknowledge the complexity of the world and resist the impression that you easily understand it. People are too quick to accept conventional wisdom, because it sounds basically true and it tends to be reinforced by both their peers and opinion leaders, many of whom have never looked at whether the facts support the received wisdom.
What is the annual average rate of return for the market? 10.00%? 12.50%? 15.00%? This is one of those "facts" that investors hear from friends, the media and the investment industry, and it is usually wrong.
Would you believe it is less than 6% per year? Sorry to break the bad news, but the stock market’s historical data confirms it.