“Quantity has a quality all its own.” Hence 75 million patriotic Americans each with an official standard baseline - featureless - fighting rifle is indeed a force that a regular military with full auto and such would find a genuine threat. 2A does have that collective factor as well.
TDF INDEX: Cats, Guns, and National Security: THE DAILY FUDD index. https://catsgunsandnationalsecurity.blogspot.com/2021/03/the-daily-fudd-index.html