Goodness what a lot of opinions.
I am a female audiophile. My reasons are the same as men's -- I love music, and a good system makes it so much more enjoyable and engaging.
As for why there are not more female audiophiles -- well, the attitudes expressed here have a lot to do with it. Women are hyper-aware of where they are welcome and where they are not. If they sense that it's a "boy's club" and that they are going to be made to feel uncomfortable, they are going to shy away.
I attended an audio society meeting in my area for the first time a couple of years ago -- it was intimidating. I walked in as a new person, and the person signing me in asked me "who are you with?" It was assumed that I was the wife or girlfriend of someone who was already there.
Most of the people there were very nice. But the "barriers to entry" are huge for most women, who do not want to be the unicorn, regarded as an oddity.
That said, I hope more women do get involved. Some of the comments here, full of stereotypes and assumptions, are an indication that too many audiophiles have not encountered any actual women in the context of their hobby, and it would be a healthy thing if they did!