My DH bred with trash not once, but twice. One trait both BM's shared was a lack of education, or even an understanding of how important education is and wanting better for their children.

BM1 chose to live in one of the worst neighborhoods with one of the worst school districts, and pulled OSD out of middle school after she got into yet another fight and slammed a girl's head into a restroom mirror. Instead of addressing OSD's issue with anger and poor social skills, she signed her up for school via correspondence (pre internet days). OSD spent her adolescence at home, further isolated and living in her own head. I believe this was when her narc traits really started to flourish. She was never involved in any group sports or activities, and ended up with a high school diploma despite being barely able to read or write. She's not unintelligent, but she is stunted.

BM2 didn't graduate high school. She was in the foster system, got knocked up, and married to get out. She allowed YSD to miss a lot of school, mostly Mondays and Fridays. YSD had terrible grades, huge learning gaps in math and English, and poor study skills. YSD was never enrolled in any extracurriculars, but learned a lot about makeup, hair, and how to catch a man from her mom. She moved in with us two weeks before starting high school, and it was a struggle to getting YSD through those four years. The school basically gave her a pity diploma.

He needed a Vacation before the Vacation.   
you must totally disengage from all of this.  Just make sure he does not live with you.  After CS stops BM will not want him.  
he is 17. He will live the life he chooses,  uneducated, manual labor, type of life, 

Houseshitter.. lol

My ss15 tries to pull this crap all the time. Luckily I have my claws into SO enough to keep that from happening. But ss15 would drop out right now if he was allowed. I do hope they give him a pity diploma because right now things ain't looking good on him actually earning it.