I would argue that the reason men are the largest demographic is because the female market is largely untapped. Most of the men I know grew up playing games with "boy" themes (ex, racing, fighting, shooting). Now that they are adults, they have a huge index of AAA games that cater to those same interests but at an adult level.

Meanwhile, myself and the girls I grew up with used to play dress up games, various Barbie role play games, and animal rescue games. But as we grew up, there weren't many adult PC and console games that catered to those interests. Most of my childhood friends eventually stopped playing altogether.

The one exception is the mobile market, where women make up 55% of players. And surprise surprise, the mobile market is the one platform where you find an a variety of girly games. If you build it, they will come!