Honestly, this is what concerns me most about China. There are literally 30 million more men than women. That's equivalent to the entire population of a mid-size country who will never marry. Add in unemployment and drugs, and you get an extremely combustible situation.

The rest of the world should worry, too. There are countless examples throughout history where wars have been started to put a lid on internal unrest. What's more, unmarried men are inevitably the ones sent to fight, so it's a solution that kills (pun intended) two birds with one stone.

Polyamory is fairly rare in human societies, the link you pasted talks about polygamy. Polygyny has been practiced in a few societies and the numbers would be too few to conclude anything.

What might stabilize is it legalized sex work.

It's legal if you have the will. Most men don't want to meet prostitute. I think they have the desire to be desired, for what they are, and not for their wallet.

At some point when going out isn't any fun there's not much to do but polish your rifle and your gun.