My predicted half time is under 2 hours and I was sedentary for years before starting to run 9 months ago, and I'm 40 years old.

Endurance sports are quite accessible and don't require that much time, effort, or talent to get way better than the vast majority of people, it's just consistency.

I've been an endurance athlete most of my life, running 100 miles at 17, a 5:30 mile at 50, and lots of other stuff in between. I know that a 9min/mile pace is "easily achievable" by many folks, which is why I noted that millions or billions of people could do this. Nevertheless, I think it is really important to not overstate how achievable this is - there are many more people who could not do this than could, I think.

FWIW, that now includes me, as a 62 year old. I can hit 6:30 pace for 400m, but find it almost impossible to get under 10:0x for a mile. And that's even after 6 months of training for a 50 mile trail race.