How to make a “gun tax” palatable to the public?

I would like to know how the proponents of such a “gun tax” would respond to this question. It is the same thing as the “sugar tax”, but I think the response would be very different. The people who think that a “gun tax” would be good have never actually tried to purchase a firearm, or seen what one has to go through in order to purchase a firearm. They think that guns are so cheap, and so readily available, that they are a problem and a menace, and that people shouldn’t own them. They don’t understand that many people can’t afford to spend hundreds of dollars to purchase a firearm, and then go through a waiting period of days or weeks, and then have to go through a background check at the gun store, and go through a mental health screening, and get a safety course. So my question is, how would they respond to someone who points this out?