You can see that for holding periods of less than 9 years the stock strategy is a lot more risky than the bond. However if your holding period exceeds 9 years the stock strategy is both, less risky and yielding better returns. Also notice that in long term, the width of the yield distribution for the stock strategy is about the same as for bonds, but overall it is located above bond yield distribution.

What does it all mean for regular folks that are trying to save for the retirement? Don't worry about whether the market is trending up or down, it's in a bubble or a recession is coming. You will never be able to time the market. But putting money in stocks and not touching them (other than reinvesting dividends) for long periods of time will ensure that your hard-earned money will not be lost, also giving you a chance to earn quite a healthy return - no downside and all the upside.