Centuries of enforced monogamy is to be blamed for the 80/20 rule.

Enforced monogamy really ruined the gene pool by allowing undesirable men to reproduce.

Back then women married simply because there was a strong pressure to get married early and raise a family. It had nothing to do with the mans attractiveness and everything to do with his ability to provide for his family/his values.

Now the average beta bucks faces difficulties in compensating for his lack of physical attractiveness through financial means, as his predecessors were able to do. As they're frequently constrained to minimum wages now and the pressure for women to marry early is just not there anymore.

So it's not a surprise there's a rise in the number of virgin males well into their mid-20s now.