Having superior numbers isn't everything, and institutions in the real world are led by minorities, not majorities anyway. A company is managed by the board, not the workers. A kingdom is ruled by nobles and royals, not the serfs. Soldiers are sent into the grinder by their superiors and they rarely get to disobey despite having all the guns. It seems all it takes to rule over many is having a formal authority held up by an abstract concept of legitimacy.
I think it's perfectly believable that in an alternate fictional world the few males could capitalize on their own scarcity and become an elite caste that holds a lot of power.
None of that is even fractionally equatable to what's being talked about.
A birth rate of 1 in 5 means that for every 50K people born, only 10K of them will be men. Even in a picturesque world where men never die during birth, they're not infertile and all the other problems that would make this bad... you're not looking at much bigger numbers.
That means 80 percent of your population isn't reproducing. That means that your society is literally rotting away to extinction. This schism becomes more drastic the smaller the number gets. Say you had a small village of about 500 people, yeah? You have 100 men, again, assuming none of them die during birth or get sick or injured and die from that, are infertile etc. etc. If a fight breaks out with a neighboring village, who are you honestly going to send to fight? The 100 men barely keeping your village alive or the 400 women, most of which won't even be having kids?
After you win that fight, what's the next course of action to secure your village's survival? You take THEIR men and you use them for breeding fodder with the other resources you've taken. You then continue this cycle of winning and taking until your village is the dominant village in the area or at least big enough that other groups don't mess with you. This is how ancient man built up their land and kept themselves alive, killing competition, cutting off their ability to breed and then outbreeding them.
This isn't about a bigger number meaning strength and power, it's basic logistics. Women HAVE to be the dominant hunters, gatherers, protectors and so forth or their society gets
wiped out. You can't risk what few men you have dying doing dangerous jobs because losing a single one of them has drastic effects on your people and their future.
Sure, maybe you could have egotistical guys in this world but they sure as hell wouldn't be free while doing it. They would be objects of survival, kept and guarded and won by only those who could prove they were worth the resource, much like how our ancestors competed for women they would absolutely do the same if not more drastically since there's far fewer men in existence. They'd be symbols of status at best and used like tools at worst (that's the hentai scenario).
Yeah, one woman. And the way I see it, she was more desperate than aggressive, going after the weakest in the herd, and she backed off once she saw that the guy was taken. If MC was assertive, he'd put her in her place.
Actually, I can agree that this is a wasted premise, but for me it's because this reads like any other harem story where a flock of girls goes after a perfectly average and lame dude.
As one of the earlier comments pointed out, aint no way in hell monogomy would exist in this world. It would be detrimental, completely detrimental. But the author wrote it in anyway. I can tell what he's going for, but the premise goes much deeper than what the he is clearly trying to portray and that's purely wasted potential.
Edit: Calculation correction
