Why do some sources say women make up ~50% of gamers?
And then they vaguely detail their definition of gamer? To me I wouldn't call people who occasionally play games on their mobile phones to be gamers.
I think a much more accurate snapshot of the demographics is seen within GameSpot's About page:
96% of real gamers are male. The ones that know about the major platforms, titles, read previews/reviews, watch trailers, etc.