It's difficult to draw many lessons from 2008. The people who suffered most then were over extended home owners. It's still not a good idea to be one of those people but there aren't so many of them now anyway.
A lot of people _need_ the S&P to stay where it is to keep their standard of living stable. If it drops to a rational valuation (say, 2500-3000), there will be a lot of pain.
