1) When you travel with people who have likeminded travel ideas, you can work together to make the most of your trip.
2) You can make new (international) friends.
3) In case you decide to travel to a region which is considered not entirely safe, traveling in a group offers you a bit more security.
4) You can learn from each other, as everybody will contribute ‘something’ to the group. Whether it’s an extensive knowledge of the local culture, a native speaker of the language(s) of the visiting country/countries or a certain ‘outdoor’ skill.
5) You can share your experiences with people who can appreciate them. I always found it difficult to share my travel experiences with friends and family back home, who couldn’t get a clear picture of what I had seen and been through.
Traveling with complete strangers, can at some point be testing and annoying. On the other hand, you can feel the same way when traveling with friends. All I can say is, when I traveled with strangers, it really added value to my trip.