They have nothing better to do.
It is all about drama in most cases.
They like to have interesting stories in their lives, so they instigate fights and create drama and chaos. I see many drama queens in my life; the one that amazes me most, I call 'Mean Girl'. She works at the same company I do. (I was going to write, I work with her, but she can't work with anyone female, she gets along and flirts with the men) She rats out her female co-workers and lies to the bosses, starts fights and bosses some woman around. She's truly malicious, and the men ignore her behavior towards women, even the bosses! Drama and Chaos! She loves it.