If nobody can predict the market, why expose yourself for a long time? Because you think the various risks will even out and it will inexorably rise over time? Is there not less risk in being in for shorter periods, and trading events that have well-defined outcomes, as long as those outcomes continue to be predictable? I liked chemical reagent's frankness, that he could predict what was going to happen only so long as the current pattern held.
The macroscopic historic pattern is gone. Things will have to be re-examined, models re-worked, the meaning of data re-interpreted; all of this is in fact occurring even as we speak, but the change is sufficiently rapid that validation isn't good, and even good models are quickly outdated.
In order to make money by "predicting" the market, you need to be able to accurately guess ups and downs. You make assumptions when you say that short periods have "well-defined outcomes". No they don't. Very easy to get the timing right even if you have the logic right when dealing with very short time periods. It's a long period of time that smooths out the risk (again, keeping other aspects of your financial house in order). While the past is no GUARANTEE of future events, it does provide a good likelihood of future events...if not the exact percentages, the overall up or down of the market. Regardless of how things have changed, we would have to dramatically change the way we do business for companies to stop making money over the long haul and thus seeing the markets rise over the long haul. The period from Oct. 2007 to March 2009 was the worst for the market since the Great Depression (some would argue 1987, but that was pretty quick), and if that's the worst, it's really nothing. Would have been a drag to be retiring right then, but that's why you retire debt free and make sure to have 3 YEARS of expenses saved. Gives you enough time to let the market bounce back. IF the market scares you, then retire debt free and have some other way to pay your bills...either live on the cheap so that you can live on Social Security, have rental properties that bring you money or some other thing that generates income, or simply save a pile of cash that you plan to use that will lose power over time.