That metaphor breaks down here and is not really applicable. If two people are chained to each other at the ankles, they can both plausibly argue that the only way to save their own life is to take that of the other person. Whining "but I'm the good guy, I deserve to cut off his foot and let him be the one to bleed to death" is asinine.
The solution here is, of course, to not be chained to the other person irreversibly. But any time that is suggested, we hear a bunch of "We're stronger together, that's crazy talk!" And here we are. 330 million people all chained together, and now people are upset that the other team has the hatchets and is menacingly staring at their ankles.
>and another significant percentage of the population is not yet old enough to vote
Not sensible enough to vote. Don't leave that part out.