Some people just take themselves too seriously. This isn't exclusive to cosplay. You will find it at work, at school, at the shopping mall, or in any sub-culture, really.
I had a horrific time at Anime North 2009 because I chose the wrong people to spend time with. But other than that, any time I've had a conflict arise with other people I know from cosplay or cons, it's generally been about personality clashes rather than anything motivated by the hobby itself. If you remove the actual issues of cosplay and just deal with people as people, I find it becomes easier to sort out most problems. I've said this before but most of the time, it's not really about the costumes.
I've also been pretty vocal about calling B.S. on things in the hobby that I find to be problematic, but surprisingly it's never resulted in infighting with other people.
As an aside note, the word "drama" bugs me. I feel like it's a bit of a buzzword. Far too often, I've seen it being used by people who like to place themselves above infighting and other issues while still actively adding to them.