Another factor is that people literally aren't aware of their personal problems, only of some of distant consequences. If anything, smartness acts to cover up the evidence via rationalization.
Friends know about some of them, but they tend to discuss these only in one's absence ("the problem with X is that he is always [blank]", etc.)
He will solve all his own problems in that category, and fewer outside it.
So of course, after he's spent a long time trying to solve his own problems, the remainder will be ones he's bad at.
But for other people, lots of their problems will be the kinds he's good at.