One way to deal with a sarcastic troll. Overlook that they're being sarcastic and take them at face value. Ask them to support their statement.

You think driving kills more people than guns?

Okay. Then let's license drivers. Require them to take training courses. And pass tests to prove they can use a car safely. And make places where you can't bring a car, so it's safe for people to have picnics or take a walk or ride a bike without fear of being mowed down by a car. We shouldn't allow cars on sidewalks, for example. And on ball fields and playgrounds.

You could try to prove that cars don't kill more people than guns, maybe they do maybe they don't. But activities that are dangerous even lethal must be regulated in a densely populated world. Might have made sense when people were scattered about. But we live close to each other, that means guns are often used without much thought or need.

We really need to consider, soberly and seriously, without sarcasm and ridiculous analogies, if we really get anything in return for the death and fear guns cause.