I would take a wild stab at saying i think maybe 20-25% of gun buyers are knowledgeable about what they are buying, most don't even try to research a weapon or caliber past maybe reading a single article on a particular weapon if that.
it was about the same thing when I was in the gun business years ago.
someone would come in to look/ buy a weapon and the first question out of my mouth was usually well what exactly do you plan to use the weapon for? whats it main purpose?
most just stood there with a blank stare, never considered that.
and of course we have a huge airport here, a ford factory and so we had a bunch of manly mechanics that would come in and ask for a 2 inch model 29 S & W for the wife to use as a home defense gun or to carry in her purse--Because the guys they work wiht told them that was the best thing since sliced bread.
just being around a gun shop or range it doesn't seem a lot has changed over the years.