OP, I taught my younger brother to drive when he was 17 (many years ago). I know all about the invincibility of the young male.
One of the things that really hit home with him, albeit in the context of speeding (although I think it would be the same in terms of drinking and driving), was when I talked him through what would happen to him and everyone else involved if he ever ran over a kid who just happened to run into the street in front of his car, laughing and not looking.
I wasn't patronising about it, I just calmly talked him through the reasonable consequences.
He hadn't thought, just hadn't thought, about what would happen to our parents, the child's parents, the child's siblings, his own job prospects - let alone how this would sit on his conscience. I was a bit alarmist (but only a bit) when I reasoned about how fine the line is between negligence (as you'd want to explain it to yourself) and murder, when you deliberately or unthinkingly decide to speed (or drink and drive).
He came to his own conclusion that it simply wasn't worth it.
Bright teenagers would, I think.