Guns are ideal for opportunists.
One pull of a trigger and bam, you've either seriously injured or killed someone.
A knife or a pretty big rock to bludgen with are in comparison riskier. Unless you're someone straight out of CS:GO, you're likely to not know how to kill someone cleanly with a knife: it'd take several stabs which offers the victim a chance to scream or retaliate.
That's why there's an issue with guns, in my opinion. I'll give another analogy:
You have an exam coming up. You're allowed one flashcard of notes, so you cram it with writing and bam, you've gotten an A+.
You have another exam, no notes allowed. The only way of getting notes in is by smuggling in a phone, writing it on your waterbottle, or other ways of cheating. And that's not only risky but it takes effort and skill to not get caught.
Firearms provide a simple solution to one's problems. I'm not saying all American people will resort to shooting the ice cream man for running out of 99s, but if someone has a fit of anger, decides to get high, is peer pressured into doing it, too drunk to see the implications, etc... then you've got someone who's dangerous.
Yes - there are gun laws which prohibit 'unstable' people from getting weapons. But it only takes a few pints, or some friends calling you a pussy, or being so overcome with anger to
become unstable, even if it's only for a few minutes.
That's enough time to shoot someone dead.
I found this article by the New York Times about how mass shooters obtained their guns. It's pretty interesting that a lot of them got their guns legally, including the Orlando shooter.
"Mr. Mateen legally bought at least two guns, a federal official said. “He is not a prohibited person, so he can legally walk into a gun dealership and acquire and purchase firearms,” "
https://www.nytimes.com/interactive/2015....html?_r=0