On the other hand, that doesn't explain everything. As the computing industry has become bigger and more lucrative, it has also become less like a gentleman's race and more like a cage fight. The primary mode of interaction has shifted from collaboration to competition. There are always more projects in any given space, creating more factions each more determined to sling FUD at each other so that their project and their investment in it stay relevant. There are more sub-sub-domains of knowledge, with those on the peaks of each sneering at the others. The environment for women has become measurably worse than it used to be; I worked with a higher percentage of women on Encore's kernel team twenty years ago than I do now even at Red Hat. It's a nasty, aggression-soaked environment, and anybody who doesn't believe that must not have read the other comments on this very page. I can tell you, it didn't used to be that way.
Programming as an activity has its ups and downs. Programming as a career has started to just plain suck.