I think “a billion people in the world” is wrong here—it should only be about 75 million by pure multiplication.
They might have been talking about the total amount of people with the potential to become better than you at the specific thing rather than the pure percentage of people who would be if everyone tried.
Meta: I would enjoy seeing growth in the number of users with everyday objects as names. I look forward to one day seeing the HDMI Cable, the USB-C Adapter and the Laptop Bag in conversation with each other.
Maybe but the US number lines up with 1% of the population lines up with the top 1% figure; if people outside the US are ~50x as likely to be top-1% at various hobbies that’s a bold statement that needs justification, not an obvious rule of thumb!
Or it could be across all time, which lines up with ~100 billion humans in history.