Actually, there is a clear link between mass shootings and mental illness:Checking Facts and Falsehoods About Gun Violence and Mental Illness After Parkland Shooting:
According to our research, at least 59% of the 185 public mass shootings that took place in the United States from 1900 through 2017 were carried out by people who had either been diagnosed with a mental disorder or demonstrated signs of serious mental illness prior to the attack. (We define a mass public shooting as any incident in which four or more victims are killed with a gun within a 24-hour period at a public location in the absence of military conflict, collective violence or other criminal activity, such as robberies, drug deals or gang turf wars.)Mass Shootings: Maybe What We Need Is a Better Mental-Health Policy – Mother Jones:
...Both rates are considerably higher than those found in the general population — more than three times higher than the rate of mental illness found among American adults, and about 15 times higher than the rate of serious mental illness found among American adults.
Nearly 80 percent of the perpetrators in these 62 cases obtained their weapons legally. Acute paranoia, delusions, and depression were rampant among them, with at least 36 of the killers committing suicide on or near the scene. Seven others died in police shootouts they had little hope of surviving (a.k.a. “suicide by cop”). And according to additional research we completed recently, at least 38 of them displayed signs of possible mental health problems prior to the killings. (That data is now included in the interactive guide linked above.)
In an analysis of 235 mass killings, many of which were carried out with firearms, 22 percent of the perpetrators could be considered mentally ill.I believe, as most Americans do, that improving gun regulations will reduce the number of mass shootings. Part of the solution is making it easier for people with mental illness to get help and harder for them to get guns.
'Red flag' laws gain momentum in states:
A week after Florida’s legislation was signed, a Broward County judge in Florida issued the state’s first order to temporarily remove firearms from a man who allegedly believed he was being electrocuted by condominium electrical breakers and targeted by the FBI and a shape-shifting neighbor, according to the South Florida Sun Sentinel. Four firearms and 267 rounds of ammunition were removed, and the man was taken to a hospital for involuntary psychiatric treatment.