Going out-of-my-way to be fair, I suspect that sort of thing is the same reason why I have multiple digital music players, and multiple pairs of headphones, despite only having one pair of ears. Some people get obsessive about collecting things, for whatever reason.
That's why, in my opinion, gun-control is partly about preventing people picking a potentially lethal object to get fixated on. If you don't "hold the line" by restricting availability of guns from the start, people with a tendency to get obsessive about collecting things will get obsessive about collecting firearms, and you will end up with a gun-lobby that makes it hard to introduce new restrictions. If guns aren't available those folk will pick something non-lethal to fixate on.
And I also suspect that when people own a large number of them, and start to obsess over them, it creates its own temptation to use them. That guy who shot all those people at that music festival (using bump-stocks) seemed maybe to have a bit of that going on (IIRC he had a preposterously vast collection of guns).