you are wrong.
example:
two kids are walking home from school and get into an argument, A punches B. B fights back, gets A on the ground and starts to choke A to death.
A does NOT have to let B choke him to death, just because he punched first. That’s absurd.
A does NOT have to let B choke him to death, just because he punched first. That’s absurd.
It's illegal for "kids" to have guns. If A is able to grab a rock and whack B in the head to stop the attack, he/she defended themself. If B dies, there will be an investigation to see who started the fight that ended in death. Your scenario rarely ends in a fatality unless A then turns the tables and beats B to death "in self defense." If A shoots B dead, he/she broke some weapons laws and has a whole slue of legal problems ahead.
If you would like to try out another analogy, I understand. That one was terrible.
If you are the aggressor, if you are guilty of battery and/or assault and then lethally defend yourself when the tables turn, the castle doctrine does not apply. Hypotheticals are largely ineffective at finding fault or justification for a law. The only reason these laws are needed is because DAs, attorneys, LEO apparently can't be trusted to make good judgments when enforcing some laws. It's the same reason kids get kicked out of the public school system for sharing aspirin (drugs). Zero tolerance laws absolve administrators from having to demonstrate good judgment as a qualification for their position.