Balanced advocates for gun control (most Americans and police force) seek fair measures to make everyone safer. The Second Amendment protects one’s right to self-defense, and simple rifles and handguns accomplish this.
The most effective gun control measure is to ban military-style weapons (and accessories) for civilian use, making it harder for mass murderers to quickly and easily kill many people.
There are three reasons to use military-style weapons: a belief in needing protection from the government and/or a post-apocalyptic society someday; enjoyment; and mass murder.
Yes, disturbed people are the core problem, and measures addressing mental illness are needed in addition to gun control. However, in half the mass shootings from 2005 to 2018 there was no clear sign of mental disturbance beforehand.
Whether or not to easily, legally arm people with weapons of mass destruction is the choice at hand.