IMO, this is a conservative way to increase your retirement spending. Let's take and example of 62 yo a retiree with $1 million saved and SS of $25k a year at their FRA of 66.
If they take SS at 62 and use a conservative 3.5% WR, then their inflation-adjusted spending can be $53,750 ($35,000 from portfolio and $25,000*75% or $18,750 from SS).
Alternatively, they carve out 8 years worth of age 70 benefits into a separate fund of $264,000 to provide $33,000 a year for ages 62-70 since their age 70 SS benefit will be $33,000 ($25,000 * (1+(8%*4))). They have $736k left and at a 3.5% WR that is $25,760... add the $33,000 and the total is $58,760.
So with some minimal financial engineering they have increased their retirement spending by 9.3%!
(I'm assuming that the $264k side fund earns the inflation rate so the $33,000 a year can be increased for inflation, but even if you bumped the $264k up a little bit to consider inflation more explicitly, it is still a winning strategy.)
The numbers bear out your strategy:
264,000 @2% less 33,000(annual withdrawal for 8 years) = ending balance of 26,125.
736,000 @6% less 25,760(annual withdrawal for 8 years) = ending balance of 922,730
At 70, SS of 33,000 plus 33,209(3.5% of 948,855) = income of 66,209
1,000,000@6% less 35,000(annual withdrawal 8 years) = ending balance of 1,203,973.
At 70, SS of 18,750 plus 42,139(3.5% of 1,203,973) = income of 60,889
This is roughly 8% less income than the wait to 70 approach.
Your heirs may prefer the take at 62 approach as it leaves them almost 300,000 more, but you live off of 6000 less per year to make that happen.
The person that claimed at 62 would need to increase his WR to 4% to match the income of the person that waited til 70. 1,203,973 x 4% = 48,158 plus 18,750 SS = 66,908.
VW