How to tell my family that I want to join the military?

My family is kind of between middle and high class in financial terms and both my parents are working and earn pretty well enough
In my country , we can join military in 2 ways
One is you can be an higher ranking "officer" and other is being a normal soldier

The test to be an officer involves too much talking and things I personally just can't do it, also my wish is to be the 2nd guy , that is, normal soldier
Now the problem is, in the 2nd case you are initially given the lowest rank in the military plus you will have very less salary and you are the person who must be ready to kill and die anytime for the nation..
So my parents can never willingly support me and let me take the 2nd option and from my experince you just can't win arguments with them also since you are living in their expense
So since I am 21, should I leave my home?
How to tell my family that I want to join the military?
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