Do I really need a guide for trekking?
That depends on a few things.
1. Where are you going? If you are going into popular areas, a guide might not be necessary to show you the way. However if you do want to get insights into life in Nepal and learn more about the culture, a good guide is invaluable. It does come at a small cost though.
2. What your interests are. If you only want to tick Nepal off the list with a few photos to prove it, we'll. The guide can only take pictures for you.. So not required. However if you want to enhance your trip with local knowledge, invaluable
3. How concerned are you of safety? Local guides know the terrain, understand the weather more, can crisis manage if there are problems. You cannot.
Top tip: ask about guide qualifications and experiences before you hire them. Not all come with these qualities.