Guns are fun

Guns are, indeed, fun. I've definitely enjoyed my self with them. But that in itself is not an argument for their existence. You might say that their net amount of enjoyment created outweighs the suffering caused, but that's and example of Induced demand. If they didn't exist people would find something else to be passionate about and enjoy.

This argument may seems frivolous, but is a major obstacle often to pushing back on guns. People get very attached to guns are part of their identity, culture and life. Changing culture is hard.

Note: This same argument can be applied to many other types of "harmful" things that people like.