I think that's the definition of effective. Someone breaks into my home high on pcp, the most effective way to stop them hurting my family is killing them. Is that not a true statement? What is a more effective way to do it, knowing that failure potentially means the death of your kids? I'm not going to engage them with a tazer, there's the chance they will walk right through it, then what?
Anthony Smith, the current #5 ranked light heavyweight in the UFC is 6'4 and probably walks around at 230lbs. A guy on drugs broke into his house and Smith fought him and could not put him down. This is a guy that could defeat 99% of people on earth in a fight. Why would a normal civilian choose to fight a home invader with their fists when a more effective option is available? What if 2 people break in?
"Can I decide that only owning a gun is not enough against the other gun owners so I need something more effective?" I don't think firing a rocket launcher at someone in your house is going to be as effective as a firearm due to the potential for collateral damage. Also tanks play hell with my new wooden floors. Claymore mines are always a risk when stumbling around in the dark. There is no other rational more effective choice than a firearm for someone defending their home.
The context here is owning something to provide "effective self defense" - so where do we draw the line? Can I decide that only owning a gun is not enough against the other gun owners so I need something more effective?
GP's claim is this right justifies owning a weapon that can easily kill. That's far beyond "effective" in my view.