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 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.