As a historical re-enactor, I've heard the whole, "a person doesn't
need ____" question countless times. And I don't even mean guns, either. People have applied that to former warplanes, Jeeps, what have you. One smug lady asked how it was legal for us to own WW2 wool uniforms. Really, how do you respond to
that? Thankfully, another spectator took her to task on that and left us out of it.

I grew up doing civil war re-enacting and my dad built his own 6-pounder field gun. We used to run into people all the time who went bonkers at the idea that almost anyone can own one and there's no registration like there is for breech-loading artillery. Once they saw how long it took to load and fire it, some questioned us even then, about how nobody needs one. As a ten-year-old at an event way out in the sticks, I honestly asked one man, "If you don't think we need this stuff, why'd you drive way out here to watch this re-enactment take place, then?" Several people applauded that as the guy skulked off, outwitted by someone a quarter of his age.
In a recent editorial, someone went out of their mind when they found out you can buy a tank if you have enough money and no permit is required (true, just as long as the armament isn't fuctional). Said writer didn't seem to grasp that a Sherman tank is no more dangerous as a bulldozer, because hardly any have working weapons (and those who do have full registration with the ATF). Just like how none of the current flying P-51s is dangerous
unless it crashes into you.