The 'lost decade' issues only have previously applied if you dump all your money in at a specific timeframe, then never contribute anything else. Or, alternativ

The 'lost decade' issues only have previously applied if you dump all your money in at a specific timeframe, then never contribute anything else. Or, alternatively, if you pull out a large amount of money after the downturn. Traditional 'set and forget' 401k funding would imply you continue to contribute throughout the period (i.e., dollar-cost-averaging). By putting money in during the downturn, those dollars earn outsized rewards when the market inevitably bounces back. It essentially cancels out the money lost.