This is an aspect that has always been bugging me as well. There is this implied notion that for men, it was ok or even encouraged to be nerdy and spend all their spare time in front of a screen.

In my experience, committing to this lifestyle meant being socially crowded out. Some people were unpopular to begin with and sort of found refuge in the computer world out of necessity, some of us accepted being unpopular/uncool because we did not care.

One possible explanation, but potentially an offensive one, and only based on personal experience: fewer women were willing to make this sacrifice, at least in school. Interestingly, this was not because boys would be unwelcoming but because other women would judge them harshly for stepping out.

On a related anecdote, I frequently observed girls in school downplaying their math abilities in front of their friends - not because men judged them, but because they did not want to stand out in front of their friends.

I suppose the interesting question is why they felt this way, and I would not wager to answer it. I just think the theory 'men are not letting women into tech' simply does not hold up in the formative school years.

Only very recently (since the social network movie) there has been this glorification of tech in combination with the startup lifestyle.