Actually they are are aggressive flea ridden pieces of shit. Totally agree with the OP and have had similar experiences. One bit me for no reason; another tried but was beaten back by a local who saw me in trouble and found a stick. There are FAR too many of them. They need serious culling. And prosecution for any local feeding them.
It will work, no matter how many of these little critters there are surrounding you. You do not cave in no matter how noisy or numerous they are. You stand tall and aggressively hold them back with body language and eye contact. Monkeys are hustlers... and they will try to hustle as much as they can. They also know who's boss too and will walk away if you keep your ground.
What they teach you in documentaries is actually true. You just need to believe it works for wild animals. It certainly works on humans too - perhaps not after an aggressor has had 20 Jaeger Bombs though
How are the monkeys with dogs? Do they back down from dogs? I think I will need to borrow a large dog in that case before I go hiking where there are monkeys...
Go hiking on Lantau or HK Island then. The monkeys in Lion's rock are really aggressive, but they don't cause as much damage as some people visiting from the north....
The alpha males are pretty scary. But I did see government workers feeding them on monkey hill. There are feeding cages there.