Most people start claiming benefits within a year of when they become eligible, although benefits increase substantially if they wait.

So the world is much more correlated than we give credit to. And so we see more of what Nassim Taleb calls "black swan events" - rare events happen more often than they should because the world is more correlated.

"Save more tomorrow" is a nudge to help people do what they know they want to do, which is save more, but they can't bring themselves to save more now. Just like many of us are planning to go on diets next month, or maybe in two months, certainly not tonight.

My mantra is if you want to help people accomplish some goal, make it easy.

If people just put away what's left at the end of the month, that's a recipe for failure.

People worry that if they buy an annuity and then die before the policy starts to pay off, their heirs will lose out. I tell them, "What you should be more worried about is if you outlive your money, you will have to move in with your kids. Ask your kids which of these outcomes they are more worried about."

I think we also have learned the lesson that we have to have better incentive structures.