Poker is a niche hobby, not some metaphor of competition in life. That picture says more about poker as a way to spend time than about competing. You might as well show pictures from a fly-fishing competition. I don't play poker, yet I am pretty competitive in many aspect of life. All I know is that pretty much every woman I have talked to wants to be more popular, more famous, more successful. And I have seen girls compete for influence, and grades, and victory in sorts from a very young age.
Go to one and tell me how many women are competing.
Here's a typical picture: http://i.imgur.com/h6cDkDB.jpg
There are zero hiring biases at a poker tournament.
So why isn't the gender distribution close to 50/50, instead of 99/1?