As I have stated before, I believe that while well intentioned, The Dude and Frank Booth are doing ThreeDee and others a disservice by just saying "invest it and forget about it". Here is why. Time frames matter. Saying that the stock market averages X% over its lifetime is meaningless. None of us have that same timeline. Timelines matter.
Here are the annualized returns over various periods since 1950
1950 - 1959 = 13.65%
1960 - 1969 = 4.39%
1970 - 1979 = 2.44%
1980 - 1989 = 12.07%
1990 - 1999 = 16.29%
2000 - 2009 = -2.23% (yes negative)
2010 - Present = 12.06%
Now lets look at 30 year horizons
1950 - 1979 = 6.36%
1960 - 1989 = 6.38%
1970 - 1999 = 9.99%
1980 - 2009 = 7.92%
These are real returns and don't even factor in inflation. Let's say you have inflation at 2% a year, then you can reduce these returns by 2%. This is just simple math to illustrate a point that those that are trying to give Threedee advice aren't telling him the entire story.
Now do not take this post to mean I don't think anyone should invest in the stock market. I am not saying that. I am saying don't by into the "conventional wisdom". As I have shown you with data it isn't always what it appears. Your individual time lines and inflation matter in these discussions.