For those who are able to choose (not taking it out of necessity), you are being asked to guess when you are going to die. Waiting until 70 gives the highest monthly payment, but not necessarily the highest overall payment. If someone take SSA at 70, but dies at 73, they didn't collect near as much as the person who took it at 62 who lives to the same age. You are literally being asked to guess when you will kick the bucket.