It goes far beyond just being poor. Wealth inequality is just one piece of the puzzle, albeit a massive one.

There are also a lot of other factors like how social media is poisoning mental health, physical and mental healthcare being expensive enough to outright bankrupt many families, the fact that rather than address these issues or limit gun ownership, American lawmakers instead think putting children through active shooter drills and locking down schools with more security than an international airport is the solution to deal with an epidemic of school shootings.

Even among nations with relatively lax gun laws, you almost never see public shootings, let alone ones on similar levels to Columbine, Virginia Tech, Sandy Hook, etc