> 11. That it happens to be a game-theoretic equilibrium to have a near-equal sex ratio, although honestly, I have no idea what things would be like if that wasn’t the case and maybe it would be fine.
Well, let's think about if this would be fine.
If there were a 10:1 female to male ratio, I think we'd expect that a modern, "civilized" society would be reasonably fine for everyone. There'd probably a lot more polygamy and polyamory than we have now, but the polygamy wouldn't be the "old school backwoods fundamentalist" type, because women would be in charge of the government and effectively make all the laws. I wouldn't be surprised if there were also a requirement that all healthy males donate at the sperm bank once a month from the onset of puberty to age 50 or so. This doesn't seem too onerous.
If there were a 10:1 male to female ratio ... it would be a dystopian hellscape that's makes me shudder just to think of it. Women would have basically no rights. There'd be an incredibly high level of violence. Nearly everyone except the alpha males would be miserable a lot of the time.
Anyway, that's my idea of how things might be like in an extreme scenario. If we're talking 1.1:1 or 1.2:1 either way it might not be a big deal, though I'd expect men outnumbering women to get bad at a surprisingly low ratio, well before even 2:1.
Note that this isn't because I think men are inherently bad and women inherently good. It's simply that nearly everyone has a very strong genetic drive to reproduce. In the world with more women than men, everyone who wants to have a biological child can do so quite easily. In the opposite world, most men cannot do so, which means reproduction is a scarce resource. And we know what humans do in response to a very strong need for a scarce resource.