And that is starting to touch on the underlying question to all of this, which is what is causing people to feel so unsatisfied and unfulfilled in the first place? Is it situation specific, such as domestic abuse and bullying, or is it a more general societal problem?

Personally I think it's the latter, and it's a massive beast of nuanced issues we don't have answers for or understand yet. It's everything from the hopelessness young people feel when looking at their career prospects in our current capitalism-fueled wealth divide, it's the modern media cycle constantly dividing us with fear, hate, and bias, it's social media warping our reality and pushing people down rabbit holes, it's the reality of being an average looking male with average intelligence and no support system settling into a life of an unfulfilling meaningless job at Walmart with low pay so he can afford a shitty overpriced apartment where he spends his free time smoking weed, playing video games, and browsing internet forums. It's only a matter of time before he has a crisis. That crisis might be getting the motivation to do something different, hitting the gym, going back to school, etc. Or it might be falling into the rabbit hole of the internet, warping his reality to blame someone else, and ultimately acting out his frustrations with the world through violence.

You take that same young man, put him in a cabin in the woods 600 years ago with an average wife, fill his days with gardening, chopping wood, raising chickens, and children, and I bet his chances of having some crisis and becoming a mass murderer drop to almost 0. There are major problems with our modern world that humans struggle to understand and aren't designed to handle. We are animals, our brains need positive feedback in the form of tangible reward from our own labors, and that is increasingly being removed from society.