Well, yes and no. Rome fell to conquering barbarian armies that they no longer had the ability to resist. Rome still had a lot of citizens, but no one was interested in fighting.
While there are no conquering armies (yet), we are being slowly boiled like a frog. And, yes, lots of people inside the gates are sympathetic to those outside. They think letting them all in, with zero vetting, will make their lives better. It won’t.
The fact that we are offering freebees also serves as a magnet. Even Rome wasn’t dumb enough to do that.
“They think letting them all in, with zero vetting, will make their lives better. It won’t.”
Just keep repeating the mantra, “Diversity is our strength.” Maybe one day it will be true.