hahah OMG, I thought that I was the only one experiencing this in Berlin. I enjoy going to tech events and very often experience what you described above. Now as a big fan of anthropology, I do not mind spending a bit of time alone and observing people around me. The key for me here is not to feel too self-conscious to be able to observe and note things and not just seem cool while self-talking myself to feeling awkward.
Anyways — I realized that unless I make the first step, there is rarely someone who approaches me her/himself. So only if I know that there are people in the room I would like to meet, I stay on. Otherwise I leave the event. Waiting and going with the flow simply does not work in Berlin.