Sure you do.
Indeed he does. If someone unduly threatens his life, he has the right to stop him as you indicated.
I am usually prepared.
I never have had to, although I came close on two occasions (thank goodness I'm big, ugly and fast).
As I have gotten older, I reconsidered that position, as I only had myself to protect with no spouse and young adult children.
Then God gave me grandchildren, so I am back in full protection mode.
God has so much invested in me that I owe it to Him to keep breathing, no matter what everyday life deals up.
I intend to do so, even if it comes to using deadly force against an assailant.