I would think that if there isn't enough money going in, people looking to make small profits per share on stocks will just keep taking money out, when stocks go up just a few pennies per share.
As an amateur trader I have done that. But now I am 100% cash. On the other hand my 401K still has money in stocks and now that I have just finished criticizing my friend, I am doing the same thing: just letting it sit there and lose value year after year.
Each time I consider bailing out I look at a few facts: (1) my 401 is heavily weighted to money market because I started with a conservative weighting. (2) I have watched the market slide a large percentage and it doesn't seem worth the time and effort to bail now.
So my question remains, how will the market bottom out if lazy people like me never sell?