My oldest didn't care about her grades. She did what was necessary to pass her classes and advance on to the next grade. She wasn't failing her classes, but she wasn't applying any of the lessons she was learning and just playing around at school. Because she had a high GPA, we didn't do much with her other than reminded her when she went to college, she'd have to buckle down and start doing the work.
Fast forward to her first year paying for college by herself. This semester I've never seen this child study more in her life - ever! She made a post the other day on social media "I'm paying the school $5000 a semester to fail" and then proceeded to say she's going to do better. Know what? On her first Biology exam (she hate biology), she got a 96.7%, the third highest grade in her class. Because she realized she's paying money and needs to not fail or do the bare minimum--this is serious.
I'm really sorry you are going through this. It's so hard when you want your child to be successful and they don't understand why you are harping on them. One day, when they are much older, he'll appreciate all the love and support you are giving him during this stage of his life
