Because it means a serious risk of the end of your life as you know it. I'm not willing to hold someone else to a standard that I know that I couldn't live up to.

If you truly believe that you'd risk your government's wrath instead of just picking the least dangerous and least likely to kill people branch of your military, then feel free to throw stones. For myself, my plan if the draft were reinstated in the US while I was still of that age was to find out how to join a cyberwarfare division, which would have led me straight to Unit 8200 if I were Israeli.

If someone told me I had to deliberately kill innocent people or go to prison, I would choose prison and it wouldn’t be close. I would also prefer to end my own life than do this.

I know it’s not this simple in matters of war, but if someone believes their government is systematically committing moral atrocities, it seems reasonable to consider civil disobedience as an option even if the consequences are severe.

You’re right that we in the US are lucky not to be faced with a choice like this (for now), but I still think it’s a choice.