Why do some bullies play the victim when confronted?

I know this girl, who is a bit (rather more a huge) bully. She bullied my best friend for being prettier than her by calling her names, talked about people behind their backs calling them “losers”, and she slept with my friend’s boyfriend trying to convince him to break up with my friend. She puts people down all the time and is generally a not nice person. But when this girl is confronted about her behaviour or someone stands up for themselves, she ALWAYS starts crying and sobbing, runs to her boyfriend or whoever and says “why are they being so mean to me and accusing me of something I didn’t do.” She always plays the victim and lies saying she didn’t do these things when she did. What causes some bullies to act out like this and never take accountability? She’s so irritating
Why do some bullies play the victim when confronted?
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