Rights and Needs

You can have a right to a thing whether or not you have or will have a need for it. So the best response to the leftist who asks, "Why do you need a gun?" is wrong question! Stop the pointless conversation right there. "The question is not whether I need one; the question is whether I have a right to one." Then explain that the right to appropriate means of self-defense follows from the right to self-defense which in turn follows from the right to life.

Depending on the sort of leftist you are dealing with you could then go on to explain why you do need a gun. But the wisest policy is not to debate leftists. Leftists need to be defeated not debated.