The dumb blonde bitch that was famous in the early 2000's was second in command of a sex cult created by Keith Raniere. Apparently she recruited around 25 young women in the film industry into the cult by calling it a self help group/women's empowerment movement. Blackmailed them with compromising photos, and participated in sexually/mentally and physically abusing them.
Pretty sure she’s as much a victim, but she did some horrible things - branding her initials on sex slaves and recruiting new victims for the cult leader
Using the fact that someone has been a victim as an excuse or explanation for the fact that they have become the abuser/bully/whatever is in my opinion an insult to other victims who have become perfectly fine and respectable people, or in some cases even role models.
In my experience, victims of abuse usually become either withdrawn and ultra nice like Wrecky's cousin or they become complete psychos like mcpoo. It's obviously not representative though, just from the people I know.