Holy judgment, Batman! I think the gnawing pain he's experiencing is the FEAR that he's a fraud (which I think is far from a decided matter). What an awful thing to call him when all you've got to go on is a couple of paragraphs.
And honestly, I think ambition is probably a prerequisite for feeling the way he feels. Unambitious people are likely immune to feeling like they're wasting time.
Working on something original, that you're the sole creator of, that you're solely responsible for, is a TERRIFYING prospect no matter how much you love the work you put into it and no matter how ambitious you are.
Calling him a fraud because he hasn't figured out how to crack the existential barrier between what he wants to be doing and what he's doing is such an oversimplification of how people work that I'm actually a little offended FOR him.
Comments along these lines only perpetuate Great Man worldviews (which I also consider a gross oversimplification of how people operate).