I'm not talking about having a generally sunny disposition, although that probably helps; I'm talking about quantifiable questions like "how likely am I to get this job?" Unrealistically high estimates could fairly be described as denial (though a relatively benign form); nonetheless they're empirically correlated with success.
I'm open to the possibility that this isn't causal, though.
They could be described with denial1, but I mean something more like denial2.
Denial2 is about not exposing yourself to feedback loops and thinking hard.
Chris Sacca who run the venture fund with the highest returns ever speaks of people strongly believing in their own success as one of the strongest signals for a good startup. But he doesn't mean that the startup funder is supposed to be in denail of reality. A good startup funder actually understands the problems that face him. He reacts to feedback.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.