I find such studies rather shallow, just explaining away a phenomenon without looking deeper for causes. I dont think the level of political animosity that the USA seems to have now has been seen before, maybe ever. In no other country have people massively defied death in the way americans do today. When people stop valuing their lives , it seems rather like a change in psychology. Maybe it's not even a political phenomenon, but an extreme expression of underlying psychological issues in individuals that express themselves macroscopically in an irrational way.