Collections aren't usually scattered around a house- the definition of 'collection' should be a clue for you.
People are fascinated by all kinds of things and guns can be interesting from the aspects of their design, machining or maybe rarity/age. People collect knives, too- it's not up to people to collect what you think and feel are valid but anyone who owns a large number of guns needs to make damn sure they don't get into the wrong hands.
You're probably not going to change any minds until and unless you address the real problem- people using guns carelessly, stupidly and criminally.
I showed the % of guns used in homicides vs total number of guns in the US, using FBI statistics of 45K gun deaths, assuming one gun is used for each and it didn't seem to make an impression- that comes to .01125%. That means 99.98875% that aren't used in homicides. Some shooters kill multiple people with one gun- kind of skews the numbers toward the "People are the problem" side, IMO.
For the cheap seats, more people are killed with blunt objects and personal weapons (fists, hands and feet- not sure why hands and fists are separate) than rifles of any kind.
I used this link instead of the one from Breitbart because you would probably crap all over me for that.
Small fraction of murders
checkyourfact.com