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.