USPSA does a survey at Nationals and publishes the results by division. (It's here, but it may be behind a membership wall: https://uspsa.org/magazine/view//2020-00#page=39 ) Open division shooters were 92% handload, 8% factory. Limited division was 76% handload. Production division was 57% handload. PCC was 66% handload. Carry Optics was 69% handload. Single Stack was 70% handload. Revolver was 94% handload. The majority of competitors in every division shot handloads, and overall it's more than 2/3rds.
Bear in mind, these are numbers that are likely lower because (IIRC) there was factory-available (Federal) syntec "match ammo" available at those matches, which is ammo that is guaranteed to make power factor (even if it doesn't chrono as PF in your individual gun) and doesn't require traveling/flying with the 500+ rounds of ammo that people bring to major matches. So there are a non-trivial number of people in those responses who ordinarily shoot their own handloads but opted for factory ammo for that particular match. In other words, those percentages likely understate the percentage of people who usually shoot handloads. It also includes a number of shooters who have some kind of sponsorship/endorsement deal with a factory ammo maker and more or less have to shoot factory ammo (or at least get it free).
I know Yager's dumb comment was about precision shooters, and USPSA isn't a precision rifle game, but his overall topic was pistols. The percentages in those surveys are pretty representative of the overall likelihood of even a moderately-committed competitive shooter (i.e., regular participant in local matches) loading their own ammo.
