War is more than just a rifle. But a rifle is needed, at some point.
The military isn't the only source for teenagers who are good at video games.
And we've seen in recent history what "guys with rifles" can do against "a weaponized elite squad". I would like to think the average American has a little bit more resources at his disposal than sand, caves, and camels.
And, don't forget, the military is made up of volunteers. even with the purge being conducted against your typical grunt, and replacements being sourced from the less able, there is still a significant number of active personnel who will not abide by what this regime is attempting to do.
If it comes down to civil war I expect a number of ex-pats to leave their posts, with or without taking their material with them. People who know how the military works, how it acts, where they store their equipment, etc.
As pessimistic as I usually am, I will not surrender to despair. I will not lay down and beg tyrants to come step on me.
