Man that's rough but honestly kind of hilarious. Those monkeys are next level clever with grabbing stuff. Learned the hard way to never leave anything small and shiny unattended in places like that, even for a second. A seagull once took my whole sandwich right out of my hand at a beach cafe. Now I just treat all my gear like it's attached to me.
Honestly that "attached to you" mindset sounds exhausting though. If you're constantly guarding every little item, you can't actually enjoy being in those cool places. I'd rather risk losing a cheap pair of sunglasses to a monkey than spend my whole hike acting like a security guard. Sometimes the hassle is just part of the story.