Why are women more attracted to bad/unhappy men?

Anonymous
There is a lot of denial about this fact but if you observe female behavior in the wild there's no mistaking it. There have been lots of studies confirming it. Here's another one I found interesting. But why, ladies? Just why?

"Women find happy guys significantly less sexually attractive than swaggering or brooding men, according to a new University of British Columbia study that helps to explain the enduring allure of "bad boys" and other iconic gender types."

https://www.sciencedaily.com/releases/2011/05/110524070310.htm
Why are women more attracted to bad/unhappy men?
21 Opinion