I do understand what you meant... but what I'm meaning is not about normal or otherwise, it is about take a criminal holding a gun. That person robs a store because they have a gun and they know it is so easy for them to pull the trigger, thus killing / injuring the other person being robbed and increasing their chance of escape from the scene. That gun makes them a criminal due to ease.
Now take the same person and give them a knife to rob the same store. See if they're just as willing with a knife versus a gun. A knife they would have to use force, skill, luck even, and effort. Also they need to be close to the person which risks them being caught, captured or having the knife used against them. Instead, a majority of would be criminals decide against robbing the store and look for other methods to obtain money, ie. working or other less violent criminal activities.
That is the difference in a majority of would be criminals. A gun can make a person a criminal far easier.
Again, what is normal? A criminal can be as normal by societies view as the next person. A good majority of criminal activity, being the big stuff that far outweighs small criminals, is done through white collar crime.
Isn't there an old saying about the richest people all having some type of past criminal activity in order to obtain said wealth? Yet these people are also viewed as the most successful of normal society.
Guns bread violence due to ease, normalcy has nothing to do with it. The most normal person as deemed by society can have a moment lapse in judgment and commit the most heinous crimes society has seen, and all due to something like a gun being so readily accessible, legally available for no other reasons than "just because."