More like 325M people in the US.
The rarity of an event does not change it's impact though. Give about 20 illegal aliens box cutters let them use them to take over and crash a few planes in to buildings one day and the next thing you know the country will be in the longest war in it's history and the most expensive war in the history of humankind. Laws will be changed, the constitution tested and trampled upon and billions of people will have to take off their shoes before getting on a plane.
And here are nearly 20 prohibited people who built their own guns, including one mass shooter:
https://thefiringline.com/forums/showthread.php?t=603981
A prohibited incel, loser who is fixated on mass shootings is exactly the kind of guy who will build his own gun.