I meet a lot of really cool and interesting people coming through the hostel. The fact that the hostel draws such a similar-minded crowd I will tout as one of our biggest successes. Of course, we have the occasional d-bag, but I can honestly say that of the 1,000+ guests that came through our doors the past year, I genuinely disliked only 3 people.
The hard part is that you develop these friendships with travelers whom you will probably never see again. It's a great surprise having friends come back to the hostel for a 2nd or 3rd time but after they leave I kind of write them off or leave them to the unfulfilling friend-dom of Facebook. I have some local friends in Medellín, but my schedule is too busy to make a lot of time for them, so they usually only see me when we host events at the hostel. So the friendships I make through the hostel are often fleeting however, in my commitment to my Medellín friends, I'm the one who's fleeting. It's not a terrible thing, but it does make me miss my friends back home more often than not.