If you’re perfectly capable of running your own retirement savings, selecting the right mix of low-cost investments, rebalancing at the right time, and not buying and selling out of fear or greed, then good for you.

But the majority of people — maybe the vast majority — are not like that. They may be smart enough to do the right thing, in theory, but they forget or slip up or are taken in by well-meaning friends bearing stock tips or annuity-peddling scoundrels who make nice to them over free steak dinners.