Anyone else refuse to care about relatives who became criminals, drug addicts, etc?

Apparently, I'm a bad guy for removing my 17-year-old niece from my life, after she got arrested for breaking her mother's nose, stealing from another student in school, kissing a little boy she was babysitting. The law where I live is too stupid to put her in prison.

From my experience, keeping malignant people in one's life is stupid and leads to destruction. Why be around people who won't help your life?