Yes they do. But those surviving longer are in the 65+ age bracket. Improved healthcare, prolonged peace time, better food and income security have increased the life expectancy of males. Now there won't be many willing to marry a 65+ year old granny
The *** ratio in the marriageable age range is now close to 1:1 with some slight variations. Generally, the developed countries have a slight favor in males as they have a better economic system, whereas in underdeveloped countries this male:female ratio would be lowered provided there isn't any infanticide that may skew the numbers.
A better argument in favor of polygamy is personal freedom and the fact that males have a generally higher sox drive with biological basis
This can help prevent spouse cheating, adultery and divorces for some.