[roguecoder]

There are a group of men who joined the profession because of the exclusionary atmosphere: it makes them feel special and elite. You can see this in the study of interest in computer science classes depending on classroom atmosphere: the hyper-masculine condition has a rise in male interest at the same time women's interest falls dramatically (http://ilabs.uw.edu/sites/default/files/Cheryan_Meltzoff_Kim...)

There are some people who just don't want anything to change and resent the effort required to think about people who are different from them, but there are others who have ego invested in maintaining the exclusionary atmosphere of the profession. I suspect, though I don't have a citation, that those people are also more likely to participate in forums like Hacker's News that reinforce that sense of being special.