There’s ~165 million males in the US, but many ex professional football players still alive and some kids who will eventually become football players. I doubt 10% of boys try out for high school or college football, but let’s say 10% make even some vague attempt.
Many people play professionally for a very short period, but arbitrarily suppose 1/7th of men are in the age range to play professionally. 165,000,000 / 2400 / 7 / 10 … So something like 1 out of 1,000 guys who make even a vague attempt end up in the NFL.
More realistically I doubt even 1% of boys ever approached football with serious intentions. Still horrible odds, except there’s a lot more athletic scholarships than openings in the NFL.
"Roughly speaking, there were 1,083,308 high school football players competing, and eventually 251 made it to pro. After simple calculation, we can get that the percentage of student-athletes going pro is approximately 0.023%."
https://u.osu.edu/groupbetaengr2367/junran-add-things-here-f...
Most players aren’t drafted. The average NFL career lasts 3.3 years. 2400 / 3.3 = 727 new players per year.
500,000 / 727 would be 1 in 687 or 0.15%.
There are ~2400 NFL players in the US, which means about 1 in 140k people.
If you figure that 10% of the people care enough about football to make an attempt, then someone who is in the 99th percentile of that group of people--someone I think many people would call undeniably good at the game, then they still have to be at least 99th percentile among those people to actually have a go of making it as a career.