Ok. So I just ran some numbers at FireCalc.
Assumed a $100K spend rate and a $2MM portfolio. 30 years. Assumed a $20K X2 for a couple taking SS
SS taken in 2024 would net an average of $5,212,067 at the end.
Then I assumed an 8% increase on the $20K over 8 years which brought it to $34.2K X 2 for a couple, but for 22 years because it would be 8 years later...62 vs 70.
SS taken in 2032 would net an average of $3,725,378 at the end.
Now, most here know that I'm horrible at math (and very often logic) so please feel free to (gently) critique.
I can replicate your $5,212,067.
For the delay scenario, you need to take the $20k divided by 70% and multiplied by 124%, which is $35,429. That results in $5,193,312... not much of a difference.
A more realistic version would be one spouse for $12,000 at 62 and the other for $35,429 at 70 and that ends up with $5,202,689. Again, all pretty similar.
Or perhaps make one spouse's benefit 60% of the other spouses benefit so $12,000/$20,000 at 62 and $21,257/$35,428 at 70 or $12,000 at 62 for one and $35,428 at 70 for the other.
Those scenarios result in $4,599,479, $4,583,986 and $4,590,059... again very similar.
All pretty similar. But what it misses is that it is highly unlikely that for a 62yo couple that both people will live to 92... it is very likely that one or the other will live until 92, it is unlikely that both will.
And taking SS later results in the higher of the two benefits for the remaining spouse and that benefit isn't captured in the numbers above. My 2c.