So, you think the US is just that much more mentally ill than every other developed country in the world?

Very much so yes.

People who are thriving and are mentally well do not just up and decide to kill dozens of people, whether it be with a gun, knifes, improvised explosive, or driving a truck through a crowd.

Access to mental healthcare of literally any sort here is basically impossible for the majority of people. Even as someone living in an area with a two huge medical campuses and health insurance, it still took many months for me to even get an intake appointment to see a doctor, just get a recommendation to be seen by a psychiatrist, for an already diagnosed medical issue that I just needed a script refill for, all because my last psych left the state.

Even then, to be able to see them at all, I'm basically in a huge pool with a bunch of other patients and don't even work with the assigned psychiatrist directly. If I wanted to see a psych 1:1, I'd have to wait even longer (months), until they had an opening.

Now, I can manage okay without medication. But if I had more serious issues and didn't have the resources to basically go anywhere I need to in the area to make appointments (car, flexible work schedule, etc), I'd be absolutely fucked. Seriously, I have every possible benefit going for me to get care, and it's still a massive PITA.

I'm sick of people saying that access to guns is the problem, not because I don't think it plays a part, but because it diverts attention away from just how absolutely atrocious mental healthcare and social support overall is in the USA. It's a lazy "solution" to an extremely serious problem, and people would much rather brush it under the rug and take the easy way out while screwing over millions of law abiding citizens, than face the reality that we refuse to take care of our population and let these issues fester until people go on killing sprees. Then when the news breaks, everyone goes on and on about how many clipazines and Assault Rifle-47s the killer had, and rarely the numerous attempts they made to seek mental health that were completely ignored.

Growing up in Colorado, I have a very personal connection with mass shootings. I was just across the street from the Arapaho high school shooting back in 2013, hearing the gunshots and having to shelter at the store I was at. Later to find out it was committed by a student with a recorded history of serious violent outbursts going back to when he was eight, and multiple serious incidents for close to 3 months prior to the attack where he was looking up pictures of mass shootings and making diary entries about plans to shoot his teachers. Columbine was an ever present specter while I was in school. I had a classmate kill himself with a firearm in high school, and watched my teacher break down into violent sobbing in our class the next day because he ignored signs in the journals we had been making for the class.

Time and time and time again, the story is inevitably the same with people committing these acts having shown serious behavioral issues for months if not years, and them going almost completely unadressed. Yes, you could remove the firearms and possibly limit the damage, but when the Arapaho shooter also had brought molotov cocktails, and they were using propane tanks as bombs at Columbine, I seriously question how much of a solution it really is given the underlying issues.