My parents are narcissists. They do it because they enjoy hurting those they have power over. They create a false image of the child and a PR campaign of the child being a wild psychopath to Garner sympathy for having to deal with such an evil child. Meanwhile they bully and abuse the child and record the ensuing screams of a terrified, confused and emotionally abandoned child as evidence.

https://www.google.com/amp/s/www.bbc.com/news/uk-england-birmingham-59489765.amp

I survived, many do not.