Here's an excellent article describing the advantages and disadvantages of drawing SS early, at 'normal retirement age' or waiting until age 70.
How delaying social security can be the best long term investment or annuity money can buy. Michael Kitces.
The author describes results under two scenarios, either SS payments continue under the same formula for the retiree's lifetime, or, that Congress cuts benefits at the widely-discussed point in the future where revenue is insufficient to fund full benefits.
In all cases the delay to break even is surprisingly long, some 20 years. But after that when the retiree is old and economic conditions are unimaginable from our present perspective, the real inflation-adjusted return begins to match then exceed what ordinary prudent investment can be expected to earn for you. The SS advantage grows year by year after that distant point in the future.
My thoughts were I don't need money now or most importantly, feel I could beat the market consistently for a lifetime, particularly continuing to make excellent investment decisions in and beyond my 80's. I saw my father do that, he kept growing a modest portfolio at a better than average rate until his advice at age 88 in late 1999 was 'this market has peaked, its unsustainable, sell everything the day I die". I did, he was right. How many of us can be that accurate, and lucky in timing, late in life? So for me I chose the more predictable options that made sense to me: Started SS at 'normal retirement age' (66) with wife drawing from mine and deferring her own start until she reaches 70.
As I said, my planning goal was to guarantee comfortable living at 80 and beyond regardless of economic conditions, and regardless of possibly my own investment errors at an advanced age. Mom made it to 98 living comfortably on a good pension and SS, her older sister is still living at 106. Finding a guarantee for my own untroubled, comfortable living (same for wife) at those advanced ages, should either of us live that long, was my planning target.
The comments responding to Kitces' article are also informative. Other financial advisors make subtle related and supporting points, for example that spending down IRA accounts before starting SS can reduce the extent to which SS benefits are taxable later, when SS is received on top of taxable income caused by the Minimum Required Distribution.
The author is a consultant to financial advisor firms, after considerable experience at the various levels in the financial advisor field.
I'm impressed with his thoroughness and expertise. He lists several credentials:
Graduate Degrees and Designations
MSFS Master of Science in Financial Services
MTAX Masters in Taxation
CFP Certified Financial Planner
CLU Chartered Life Underwriter
ChFC Chartered Financial Consultant
RHU Registered Health Underwriter
REBC Registered Employee Benefits Consultant
CASL Chartered Advisor of Senior Living