I’m not sure why you think it’s esoteric or niche, there are something like 400 million guns in the US, with 1/3 of Americans directly owning at least one gun and 44% of us households having a gun owner. I think that’s pretty far from “the vast majority” not being gun owners https://news.gallup.com/poll/264932/percentage-americans-own-guns.aspx
Moreover, lead exposure is known to cause cognitive impairments. I do agree however that most gun owners don’t shoot very often.
But if you need me to cite evidence that millions of Americans seem incapable of critical thinking you are either trolling or just not paying attention.
Here’s an entire book on the subject in case that helps https://www.amazon.com/Americas-Critical-Thinking-Crisis-Education/dp/1735942200
Finally, I’m not sure how you could construe my question as wanting evidence that it isn’t guns causing the problem, I pretty clearly asked a question, provided some links to explain what I had read that led me to that question, and then welcomed contrary evidence, of which you cited none by the way.
Thanks for being the first person in this thread to actually post some useful tips to get the lead out, so to speak.