I think he's just wired differently. Raw IQ is usually overrated IMO, but this is one of the cases where I believe the significant difference is critical.
Critical but maybe not sufficient. Hassabis claims to manage two separate workdays every day, the first spent in meetings in Deepmind's office, the second until late at night studying new papers. So not just high IQ but incredible energy too. And finally, as I understand, a highly competitive attitude.