They aren't as rare as you think. Get away from the liberal cites and go into the hinterland and you will run into the warrior culture. I grew up in it. My family comes from a long line of warriors. Back during the Yemesse War we fought the British Empire to a stand still. Unlike the Aztecs and the Inca we didn't crack or colaborate. We showed them true gurrella warfare. So much so they had to get the Cherokee and the Catawba to betray us. And we all know how that turned out for those two tribes in the end. We fought the British again the the Revolutionary war (Because Revenge is a dish best served cold) And in the War of 1812. In the Civil War we served the Union and put a boot up the Confederates asses. In World War I we put fear in the hearts of the Germans that faced us. And in World War II showed the Japanese what true Warriors were. And from then on we have served the Union as the one group that would always answer the call to battle. We abhor weakness and don't suffer traitors. Push comes to shove we will fight and die to the last man. It is our nature. But you will never understand us.
Okay, outlining how utterly unique you are unfortunately doesn't really create great confidence that that there are even 10 million people like you. And I'm not sure even you would be as committed as you say. Certainly not to a suicidal way. Hell, in your own backstory you eventually switched allegiance to the winning side!
In a situation where victory looked hopeless, I'm not sure you wouldn't be in the 90% of the patriots who decide discretion is the better part of valor, that living to fight again in a situation where victory would be possible was better than fighting in a situation where victory was impossible and your death would just long term undermine the ability of the US to continue.
Plus, liberal cities are, well, 50% of the population. Maybe 20-30% depending on how you count it. And hell, its hard to say who would be most motivated to fight or collaborate depending upon who the opponent is. And depending on who the leadership in the US was. If I was conscripted, I would be less motivated to fight as long under a Hillary President than a Trump President. Under a Biden presidency I would be fairly more inclined to outright desert since I would have zero faith in the leadership to make competent decisions, or weren't outright working for the enemy to figure out what just enough resistance looked like to transfer themselves from President to territorial governor with the minimum disturbing of their power.
As I said, there's maybe 10% of the population who are die hard Americans. My family has been in the US for about a 100 years, came over from England and Hungary in the 1900s. We have about 60 years of military service. If America goes bad, we probably move back to somewhere in eastern Europe or southeast Asia. Americans with anything like your historical family comitment to the country is, what, 50 million people who have that kind of deep connection to the country?
Hell, about 20% of the population is Mexican, and mostly came in in the last 50 years. I would not be shocked if about half of them would leave if things got dicey in the US.
Why would the US surrender to an invading force? When the people are willing to kill and invade your homeland, perhaps making your life worse then anything else?
Defending a city would be more beneficial then leaving them to die. Force the enemy into the cities.
I still doubt people would surrender As much as everyone thinks.
If someone is going to take your land and rule under a heavier thumb, why would you let them?
What % of the German population died post occupation after WWII? On either the Western or Eastern side? Unless the enemy is outright genocidal, chance of survival post conquest is above 90%.
You surrender because the pain of continued resistance is not worth whatever benefit you hope to gain through fighting. People have an awful lot to lose in resistance. Including a whole lot of politicians and bureaucrats! A chief of police has a nice house, family, and a good salary, if the salary and comfortable life comes from working for the occupation force tab rather than the American government tax, most people will chose a comfortable life.
If the president would be allowed to continue serving as president, possibly with a bigger salary, just with an appointed governor with veto power over his decisions, or he could fight to the end and be executed, how many presidents would not chose the pay out, keeping their life and 80% of their power?
Now, this is dependent upon the enemy reaching a point where people believe victory is not possible. The share of people who will stop fighting or collaborate if they think victory is still likely is a much smaller portion.
The big disagreement seems to be over how far America has to be pushed to be demoralized.