But unlike in a computer game, in the real world, that would you have labeled your enemy, does not simply disappear. If anything, you’ll create a vacuum. And I am not sure where you are taking the confidence that who or what ever feels that vacuum will be better than the status quo. The Americans have tried that in Iraq and Syria. The Vietnam war as well. And I believe the result, in every case, has been anything but that nice clean victory that “finishing off” of your enemy in a computer game promises.
In my view, this comes down to Chesterton’s fence. Before you tear down a fence, it would be helpful to understand how it came to be erected in the first place.
Please do correct me if I’m wrong, but pretty much the only time the strategy of killing of an enemy regime worked was Hitler. That was a man who applied industrial processes to murdering humans - rail networks, assembly line processing, gas chambers. This is not the level of evil we are facing here, at all.
If Putin is anything as evil as you think he is, he will surely have systems in place that will ensure the destruction of major cities in the United States in case of anything happening to him or his regime. You schoolyard, bully, metaphor, while having the benefit of being easy to understand, carries with it a risk - 1%, 5%? - that our children will find themselves in the world of A Canticle for Leibowitz.