The uncertainty is "holding off as long as you can". We don't always control when that will be.
People start dying in their 60s and 70s.
Better to take 80% of what you could get now, than to get 100% of what your entitled to after you're dead.
I'm just sayin'....
You can actually calculate how many years you would have to live to make up the difference.
If you would collect $20,000 at 62 and $30,000 at 70 (made up numbers), you would have lost out on $160,000 at age 70. It would take you sixteen years to make that up at $10,000 more dollars per year.
And that isn’t even counting the time value of money, AKA inflation.