Earlier quoted context omitted.
In my opinion, I wouldn't call what you describe "ambition", but rather "need for self-validation". Ambition is desire and determination of achieving something, whereas challenge, pressure and responsibility just seem masochistic. Where's the end goal? The problem here, in my opinion, is that the "default" goals one sees in the "start-up culture" (or the banking culture, that I'm better familiar with) are bland, spoo…
^Yes. You don't describe yourself as ambitious, you reveal it through your actions. How you prioritize. How you manage your limited time and resources. It's weird to say "I am ambitious and I waste time vegging out watching TV" in the same breath– chances are the "I am ambitious" statement is really identity performance. OP wants to be seen as ambitious (not just by his others, but by himself as well). It's a comfort…
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).