Women lived to 30 in Ben Franklin’s time. He was no looker.
Ben might not have been a looker, but he was a charmer and NOTORIOUS for his many affairs.
"Average Life Expectancy" figures from 200 years ago look bad if you don't remove the high child-mortality numbers.
Those who made it to adulthood had good odds of making it to old age. Ben Franklin lived to 84, with his wife dying at 66. George Washington died at 67, Martha at 70. Jefferson made it to 83.
When Ben advised young men to seek older women, I think he meant women over 40 -- young enough to still be fun in bed, old enough to not worry about pregnancy.