It’s not quite that bad. Life expectancy at 21 hasn’t gone up nearly as far as life expectancy at birth.

The number of men who make it to 65 after having made it to 21 is about 20% higher than it was in 1940.

And the average remaining lifespan for men reaching 65 is about 3 years higher than in 1940.

These factors certainly change the calculations, but the size of the baby boomers is a much larger factor.