You can totally trek in the Annapurna Conservation Area without a guide. In fact, I said as much in the story of the third day. Indeed, I met up with other travellers - including one who trekked solo to Poon Hill - who went in without a guide. And this is fine if nothing goes wrong. However, the value of a local guide comes in when things do not go fine. Numerous times in my trek, it was made more comfortable or safer because of my guide's local knowledge and preparation. The monsoon brings additional challenges to the trek. She could get near real-time news from guesthouses, locals and other guides on the condition of trails, and whether the monsoon had made any of them impassable. She could range ahead for help if needed, and could call for help more effectively.The higher you go and the further away from the farmed areas of Annapurna, the more it is a good idea to trek with a guide. Especially if you are trekking solo. Besides, it's much more fun to trek with a local! And it is a way to make your trip more sustainable, by supporting local guiding professions. In my case with the 3 Sisters - female livelihood as well!