You can’t make him be somebody he isn’t! And of course, it is the shiniest things that people put up front. There are are tens of thousands of students in the UC system and they do NOT all have national awards!
This is what MIT tells potential applicants:
You start with where he is: how does he spend his time outside of the classroom. If he doesn’t have something he is really excited about (and many, many students his age don’t), what kinds of things are interesting to him, and how can he do more of those things. Have him keep following a path that is truest to him. Simply to say, difficult to execute, but in the end it will get him to a place that is good for him.
ps, “STEM” is not a major- it’s made up of dozens of majors!
pps, I will push back gently on the “he’s not smart enough” description- olympiads suit some personalities / students and not others. IME the biggest differentiators as to who does well in Olympiads isn’t raw brain power but either how much the student enjoys it, or how fierce the parental pressure is.