Infatuation with "coding competitions" and high flux intelligence tasks is often an anti signal.
Sure, what they demonstrate looks good at face value, but unless you attach a micromanager over their tasks, they'll constantly deviate to the new-shiny every week instead of staying on task for the long haul.
I know even YC has been bitten a few times by accepting people who are top-performers in very narrow contexts (e.g. people obsessed with winning coding competitions every single weekend) only to see they can't do anything coherent for more than a week at a time.
Just because someone is great in a narrow context doesn't mean they can carry that over the months and years needed to deeply iterate (and suffer through the low points) on successful projects.
I'd generalize your point a little more - for a given level of life success, intelligence will anti-correlate with other hire-ability skills like work ethic, diligence, attendance, emotional stability, professionalism, etc.
Basically, imagine that there's two ways to graduate college with a CS degree - you're either the kind of person who's smart enough to get things if you work your ass off for them, or you're a genius and you coast through. If you're a genius and you work your ass off, you get a doctorate or found a startup, and aren't in the candidate pool. So you wind up with a choice about what to compromise on: work ethic, or smarts.
Ideally, you compromise on whatever makes the least difference to your organization, compared to your competitors. Hiring smart/motivated people out of non-traditional backgrounds is a great option for this.
Infatuation with "coding competitions" and high flux intelligence tasks is often an anti signal.
Sure, what they demonstrate looks good at face value, but unless you attach a micromanager over their tasks, they'll constantly deviate to the new-shiny every week instead of staying on task for the long haul.
I know even YC has been bitten a few times by accepting people who are top-performers in very narrow contexts (e.g. people obsessed with winning coding competitions every single weekend) only to see they can't do anything coherent for more than a week at a time.
Just because someone is great in a narrow context doesn't mean they can carry that over the months and years needed to deeply iterate (and suffer through the low points) on successful projects.